Undated (AP) _ On Oct. 11, 1991, a woman named Anita Hill went before an all-male Senate committee. Her vivid testimony and the discomfiting questions it raised remain with us still.

Even those who doubted Hill's allegation that she had been sexually harassed by her former boss, then-Supreme Court nominee Clarence Thomas, were drawn into discussion and self-examination.

Has this happened to me? Have I done this to someone else?

''A lot of women had felt so isolated and perhaps couldn't even define sexual harassment,'' said Helen Neuborne, executive director of the NOW Legal Defense and Education Fund. ''The hearings made an enormous difference, even though they were horrible.''

Maybe it was precisely because the hearings made so many people uncomfortable that the experience has taken root.

The number of complaints filed with the Equal Employment Opportunity Commission has since increased by about 50 percent.

Politically, the landscape has been transformed. A record 11 women have won primaries for the U.S. Senate. On the House side, 107 women will be on the ballot Nov. 3, a 54 percent increase over 1990. Many say their candidacies were directly motivated by Hill's experience.

A spate of practical handbooks have been published, videotapes produced and support groups founded for victims of sexual harassment.

''Soon after the hearing women were calling, saying, 'I think this is happening to me,''' said Jean Scherwenka, who helps run a working women's hotline in Milwaukee. ''Before they hadn't been aware of the laws. They knew something was wrong, but didn't know what.''

''What these very, very public hearings did was catapult an issue that had long been around out of the closet,'' said Nancy Kreiter of Women Employed in Chicago. ''In bringing it out, it had to be examined.''

Nationally, the number of complaints filed with the EEOC rose to 7,495 from October 1991 through June 1992, compared with 4,962 during the period the previous year.

''There's a sense now that women do not have to tolerate ... brutish, one- sided work environments,'' said Jon Patterson, acting director of EEOC offices in the Boston and Buffalo, N.Y., areas.

Whether or not Hill's story was true in some ways didn't matter, though a recent poll indicates nearly twice as many people believe her today as did with a year ago.

The point was that the cat was out of the bag. The headlines were as prominent as those about Mike Tyson's rape trial this year, William Kennedy Smith's last year, and the Gulf War's buildup the year before that.

The difference is that long after the Thomas-Hill hearings faded from the headlines, they continued to resonate. ''We have seen a remarkable staying power,'' said Karen Nussbaum, executive director of Cleveland-based 9 to 5, the National Association for Working Women.

Hill, a law professor on leave from the University of Oklahoma, has been visible on the lecture circuit. In Michigan, the National Organization for Women is sponsoring an ''I Believe Anita Hill'' anniversary conference.

The city of Los Angeles conducted a study that found 37 percent of female employees said they were victims of sexual harassment in the past year, ranging from ''sexual teasing, ogling, whistling'' to rape.

In Iowa, the governor instituted a written policy and in Maine a human rights commission found that sexual harassment complaints had more than doubled.

The Williams Cos., an energy and telecommunications business that employs 1,800 people in the Tulsa, Okla., area, decided to reinforce its sexual harassment policy by enclosing reminders with paychecks last January.

Perhaps most encouraging, volunteers say, were the number of calls from employers interested in developing grievance policies and sensitivity training. From Greensboro, N.C., to Detroit to Phoenix, demand is way up.

In Connecticut, a law taking effect this month will require businesses with 50 or more employees to provide supervisors training and education on sexual harassment issues.

Overall, however, legislative action has been slow and lawsuits, which often take years to complete, are long-shots at best.

''It's still very difficult to win a case and a lot of women, especially in this job climate, won't risk their jobs in order to give support testimony,'' said Sue Mullins, executive director of the Denver-based Women's Network of the National Conference of State Legislatures

The downside is still there. Few have forgotten the exposure and very public scrutiny Hill received. ''It's tough. It can be very hard emotionally,'' Mullins said. ''And still, I get calls from coast to coast.''