Three years ago, Amita Narielwala arrived in Bombay to meet her future husband, who had been chosen for the naturalized American citizen by her family.

Narielwala, 24, who now lives in Alexandria, said the wedding euphoria lasted only two days after the June 1982 wedding -- until her husband, an Indian psychiatrist, was granted an American visa. "His attitude changed completely. He didn't want to have anything to do with me," she said.

"He told me, 'I no longer require your support or your family's support. I'm a doctor and I can earn my own way. Thanks for the ticket to America,' " she said.

Narielwala told her story yesterday during a hearing by the Senate Judiciary subcommittee on immigration, which is investigating the problem of immigration marriage fraud.

Reagan administration officials said the problem is massive and that changes are needed in federal law to stem its growth. Sen. Alan K. Simpson (R-Wyo.), chairman of the subcommittee, said he plans to introduce a bill that would clamp down on sham marriages.

"We consider it one of the most prevalent forms of fraud that we face," said Vernon D. Penner Jr., deputy assistant secretary of state for visa services. "We consider this problem a highly significant one and one that is growing."

"Marriage fraud . . . now poses significant threats to the integrity of lawful immigration procedures," said Alan C. Nelson, commissioner of the U.S. Immigration and Naturalization Service.

Nelson said a preliminary survey conducted during fiscal 1984 in three cities indicated that 30 percent of the more than 100,000 cases in which aliens apply for immigration on the basis of their marriage are fraudulent.

But Nelson said that even when spouses come forward, as Narielwala did, it is difficult for the INS to prosecute such cases because it must establish that fraud was intended by the alien at the time of the marriage.

Jules E. Coven, president of the American Immigration Lawyers Association, challenged the government's figures, saying the problem of sham marriages is far less severe than the officials claimed. He added that, in most cases, the current system does an excellent job of weeding out the sham weddings.

But Patricia Beshara of New York City disagreed. She said that she has tried for years to get her husband deported but that the immigration service is hindered by weak laws and a lack of resources.

Beshara met her Egyptian husband in Italy in 1980, when she was teaching and he was a cook. He courted her with flowers and gifts, and doted on her. She was considerably older then he, "but he said, 'It doesn't matter. What matters is in my heart,' " she said.

After a wedding in Rome, they returned to the United States, where things immediately soured. Eventually, she said, her husband broke her jaw, cleaned out her bank account and had numerous affairs. "It was a nightmare," she said.

Less than a year after their marriage, he left her. "He told me, "The message is out that this is the way to stay in America" -- Patricia Beshara 'You're too old. I want somebody younger,' " said Beshara.

In addition to cases like those of Beshara and Narielwala, who were unwitting victims, Nelson said that Americans are willing participants in many sham marriages because they can make hundreds or thousands of dollars.

In Los Angeles, an attorney was convicted last year of arranging fraudulent marriages for Filipinos at a cost of $3,000 to $5,000 each. This year, eight persons were convicted of arranging sham marriages between Pakistanis and welfare mothers. And a doughnut shop manager in Lafayette, La., has been indicted in connection with a marriage fraud ring.

Nelson suggested several changes in the law, including a two-year conditional residency requirement for all spouses, a change in the requirement that the federal government prove fraudulent intent, and a statutory definition of marriage.

Coven cautioned the Senate that an overreaction could infringe on the rights of those who are not involved in sham marriages.

But Beshara urged drastic action: "The message is out that this is the way to stay in America."