Sexual harassment in government costs the taxpayers an estimated $90 million a year in the form of decreased productivity, lowered morale and replacement costs for workers who quit because a boss or co-worker won't take no for an answer.

This is one of the conclusions from a year-long study of in-house government sexual pressure made by the Merit Systems Protection Board.

The board, a spinoff of the old Civil Service Commission, said that 42 percent of the women responding to its survey said they had been subject to pressure, ranging from unwanted sexual remarks to fondling and rape attempts, within the past two years. Fifteen of every 100 males answering the questionnaire said they had been targets of uninvited sexual pressure, mostly from younger, married or formerly married women as well as from male colleagues and supervisors.

Ruth T. Prokop, head of the board, said sexual harassment in government is "pervasive and costly" but that it can be reduced if agencies and managers deal with it with procedures and laws already on the books.

To get a profile of the experience of 2.7 million U.S. workers, the board last May sent out 23,964 questionnaires to a select group of employes representing most agencies, regions and racial and ethnic groups to make up a national composite of the bureaucracy. Eighty-five percent responded, the board said, by extrapolating the responses government-wide, it figures that nearly 300,000 women and 168,000 G-men have been victims of some form of sexual harassment in the last two years.

Most workers said sex-related pressure came from co-workers rather than bosses. The typical male harasser is pictured as being married, and older than the women he is bothering. Men who reported unwanted advances said they most often came from a younger, married women or from several women. Minority group men reported a higher number of sex-related pressure incidents -- from both sexes -- than did white men.

Incidents of sexual harassment varied regionally, and by agency and department, according to the 200-page report, which is chock-full of graphs, charts and statistical data.

Highest number of complaints came from women working at the Department of Labor, Transportation, Justice, Defense, Housing and Urban Development and the Veterans Administration. The largest number of complaints of the "most severe" kind of sexual harassment came from women at Justice and Defense. The least number of reported complaints came from women at Agriculture and General Services Administration.

Most reports of harassment against men came from the Departments of Health and Human Services (formerly HEW), then VA. Commerce, Labor and HUD.

Forty-four percent of women and 14 percent of men responding from the metro Washington area (which has more than 350,000 federal workers) reported they had been victims of some form of sexual harassment. That is defined as "deliberate or repeated unsolicited verbal comments, gestures or physical contact of a sexual nature that is considered to be unwelcome." It can range from leering, "jokes" or intentional touching to outright physical and sexual assault. The highest percentage of reports of sexual abuse came from workers at agencies in the North Central part of the country, the least from the Pacific Northwest. Divorced or single women were most likely to report sexual harassment, and most of the harassment came from persons of the same ethnic or racial group, the study found.

Workers participating in the confidential survey were asked to answer more than 60 questions. They ranged from attitudes toward office romances to specific queries about personal experiences at work. Men in five different agencies reported they had been victims of assault or attempted rape, most often but not exclusively by women.

Of people citing sexual harassment, men reported more instances of homosexual pressure (22 percent) than women (3 percent). Although the majority of people alleging they had been victims of sexual harassment said the person bothering them was of the same race or ethnic background, 46 percent of black males reporting harassment said advances had been made by women of another race.