Convinced that a live-in housekeeper was the only solution to the problem of quality child care for her two small children, Holly Patton, a single working mother, hired a 39-year-old illegal immigrant from Guatemala in February.

The housekeeper, whose middle name is Maria, looks after Patton's home in Springfield and cares for her two children, ages 2 and 4. She reads them Bible stories in Spanish, takes care of them at night when they are sick, and sometimes even lets them sleep in her bed.

"Without Maria I would lose my job . . . and God knows what I would do," Patton said recently.

By employing Maria, Patton is violating the law, immigration officials said, because she hired her after a new immigration law was passed in November that calls for fines of up to $10,000 and even jail terms for employers of undocumented, or illegal, workers. Maria asked that her their first name and her surname be withheld because of her illegal status in this country.

Patton says she is willing to break the law because of the haphazardness of traditional baby-sitting arrangements, the strict closing hours at most day care centers and the difficulty of finding a U.S. citizen willing to live in her home.

"To me the payment of fines, or even jail, is nothing as long as Maria can be with my children and give them what I can't give them when I leave home in the morning," she said.

Patton, a 35-year-old legal secretary, is among a growing number of local residents who have tapped into a popular and fast-growing underground market for illegal housekeepers and baby sitters in the Washington area. Several local lawyers and child care experts said the demand for housekeepers continues unabated despite the new immigration law, which is supposed to discourage employers from hiring illegal workers.

The law does not determine whether a person is an illegal alien, defined as any person who illegally entered the country after Jan. 1, 1982. Instead, it made it unlawful to hire an undocumented foreign worker since November.

Many families who hired undocumented foreign housekeepers both before and after the new immigration law have chosen to "sponsor" them, a two-step procedure that takes several years. It requires getting the U.S. Department of Labor to certify that there are no U.S. workers able and willing to do the job, and then waiting for the Immigration and Naturalization Service to grant a visa allowing the housekeeper to live and work in this country legally.

Although some of the people seeking certification are in the country illegally, the Labor Department will still process their forms, according to Tom Bruening, chief of the Labor Department's division of foreign labor certification. The Labor Department will pass information about the illegals to the immigration service, but it is up to the immigration service to take action against the illegal immigrant's employer, Bruening said.

In the Washington area, where American-born domestic workers are scarce, labor certification applications for foreign-born domestic workers are almost always approved, Labor Department officials said.

The law already is having an impact on some aspects of the domestic labor market. At least four of the dozen local job placement agencies have closed or curtailed their businesses because they can be fined for referring illegal domestic workers, while some other agencies have experienced a sharp increase in requests for hard-to-find "legal" housekeepers.

In an attempt to get working papers for their housekeepers and possibly avoid fines, about 1,600 District, Virginia and Maryland families are expected to request permission from the government this year to employ a foreign-born domestic worker, a 33 percent increase over 1986, Labor Department officials said.

Richard Panati, a certification officer with the Labor Department's mid-Atlantic regional office in Philadelphia, said the number of applications from families in the District, Maryland and Virginia seeking permission to employ foreign housekeepers has increased from 859 in 1985 to 1,205 last year, and already is at 1,093 this year.

Labor officials also said they are expecting a 20 percent increase in total applications from the mid-Atlantic region from employers seeking to hire foreign workers for all kinds of jobs -- from 6,000 applications last year to about 7,200 this year -- a direct result of the new law.

In many instances, illegal housekeepers, many of them Spanish-speaking immigrants from South and Central America, have replaced the traditional at-home mother and housewife in the Washington area, where one-third of all youngsters return from school to empty homes -- higher than the national average of 25 percent -- and 70 percent of all mothers with school-age children work outside the home.

Traditionally, domestic jobs have been filled by black women. But older black domestic workers who retire are less likely nowadays to be replaced by younger black women, who increasingly are looking for alternatives to low-status domestic work, child care experts said. This void has created a ripe opportunity for foreign housekeepers.

For a weekly wage of about $200 to $250 and room and board, the illegal domestic worker cleans the house, shops for groceries, irons clothes, packs school lunches for the children, and may even drive them to baseball practice and ballet lessons. Many illegal workers have driver's licenses because motor vehicle departments do not ask whether they are here legally, these workers said.

Most employers pay social security, but no other benefits, according to agencies.

"My housekeeper is my all-purpose wife," said Betty Adler, 35, a day care operator, who is married to a Washington lawyer and has three children ages 4, 8 and 10.

For 2 1/2 years, the couple has employed Margarita Huamni, a 24-year-old undocumented immigrant from Peru, to manage their five-bedroom Bethesda home and help cope with their hectic work schedules. Because Huamni was hired before the November deadline, the couple will not face any possible penalty.

"If I didn't have her, my life would go down the tubes," added Adler, who is pregnant with her fourth child.

As is common with many families who hire illegal housekeepers, Adler and her husband Mark Rosenberg are "sponsoring" Huamni.

In the past, the immigration service rarely took action against these illegal domestic workers because there were no sanctions against employers. Now, with the new law, it's unclear whether the agency will seek out and levy fines against families who employ illegal domestic workers although they have begun sponsoring them.

Initially, some immigration experts said they thought employer sanctions alone would be a strong deterrent to hiring illegal domestic workers, but immigration lawyers and job placement agencies say that is not the case.

"When the law first came out, I thought that that would be the end and that women would have to go back to being a housewife and give up their careers," said Nancy Lawrence, an Annandale lawyer specializing in immigration.

"But what I've seen has not borne that out because people are willing to violate the law."

Larry Johnson, an immigration lawyer in Wheaton, said most of his clients who want to sponsor a domestic worker "have tried to find a {legal domestic} on their own and have given up in frustration."

Panati, the federal certification officer, said employers of illegal domestics will continue to break the law "if there's a hands-off policy" by the immigration service. "But if there are citations issued and fines levied, then you really won't see that," he added.

Immigration service spokesman Duke Austin said that while enforcing sanctions against employers of illegal domestic workers "doesn't have a high priority . . . I think there will be cases where we will have to follow through where we knew there is an illegal domestic."

But Austin added that it's unlikely the agency would check on each visa application filed by a family on behalf of a domestic worker to see if that person already is working for that family illegally.

"That would call for surveillance and we can't do that on every application," Austin said.

Local job placement agencies that used to do a brisk business placing illegal domestic workers for a fee -- sometimes as high as 6 percent of an employe's yearly salary -- already are feeling the effects of the new law.

Immigration lawyer Judith Ludwic said that in December, a month after the law took effect, she closed Apron Strings, a job placement agency for housekeepers and baby sitters that she had opened 22 months earlier.

"When the law was signed, we stopped taking applications from anyone other than U.S. citizens or legal permanent residents, and we had no {domestic workers} to refer," Ludwic said.

Some other job placement agencies report a dramatic rise this year in the number of families seeking housekeepers who are in the country legally. As a result, salaries for legal domestic workers have risen from last year's range of $175 to $200 a week for live-in help to $200 to $250 a week.

"Our business has shot up about 700 percent in terms of clients looking for legal nannies who a year ago would have hired an illegal alien," said Marla Sanders, the owner of Mother's Helpers, a four-year-old company with offices in D.C. and other cities that specializes in placing nannies born in the United States.

At Domestics by Design, another job placement agency in the District, there are 10 families for every available legal housekeeper, said Nina Marks, the firm's owner.

Barbara Powers, 45, a labor relations specialist for the immigration service who lives in Alexandria, placed an ad in the newspaper about a month ago for a live-in housekeeper and baby sitter to care for her infant son when she returns to work in mid-August. She said it seemed unusual when most of the 30 women who responded were in this country illegally. "I had people from Korea, Somalia, Nigeria, Peru, Venezuela, the Philippines and Jamaica. I had just a few legal Americans," Powers said.

Because she works for the immigration service, Powers said she was reluctant to hire an illegal so she placed another ad asking for someone who was "legal." That ad drew eight responses from people in this country legally, and this week Powers offered the job paying $200 a week plus room and board to a 57-year-old American-born woman.

Many of the sponsors and their housekeepers develop a family-like bond as a result of their work relationships. Patton said that her housekeeper, Maria, is "an absolute rare find."

"My kids are so happy now, so well adjusted," Patton said. "They have two mothers now."