In one of the first lawsuits of its kind, the American Civil Liberties Union's Lesbian and Gay Rights Project filed suit yesterday against Yeshiva University for denying lesbian and gay graduate students the opportunity to live with their domestic partners in campus housing.

The lawsuit was filed in State Supreme Court on behalf of two medical students, Sara Levin and Maggie Jones, and the Einstein Association of Gays, Lesbians and Bisexuals.

Ms. Levin, 26, a third-year medical student from San Francisco, and Ms. Jones, 23, a first-year medical student from Halifax, Nova Scotia, are both enrolled in Yeshiva's Albert Einstein College of Medicine in the Bronx. Each was denied shared housing with her nonstudent partner because they are not married.

''I walk each day among families who fill the playground and the courtyard in the late afternoons knowing that my family is not entitled to the same respect,'' said Ms. Levin, speaking at a news conference yesterday at the A.C.L.U. headquarters in lower Manhattan.
The A.C.L.U. complaint charges discrimination on the basis of sexual orientation and marital status, and seeks a reversal of the policy and damages for emotional distress and the extra cost of housing and commuting.

Ms. Jones said that she had been fortunate to find a studio apartment in Brooklyn for $825 a month but that comparable living space at the university costs only $300 to $400 per month. ''In addition,'' she said, ''I have a three-hour commute.''

The medical school issued a terse statement saying that ''our housing policy is applied equally to all applicants for student housing without regard to their sexual orientation.''

Yeshiva University provides housing for all married and unmarried undergraduates. Of the university's six graduate schools, only the medical school offers housing to students, and it does so for both those who are married as well as unmarried.

In recent years, several colleges and universities, including Stanford University and Columbia University, have granted same-sex couples equal access to benefits already available to married students. The University of Chicago adopted such a policy in 1993 after being challenged on the issue before the Chicago Commission on Human Relations by the Lambda Legal Defense and Education Fund, a national gay rights legal organization with its headquarters in New York City.

Suzanne B. Goldberg, staff attorney with Lambda, said, ''We don't think universities should be in the business of telling students whether to marry or who to marry.''

Speaking at the news conference, Michael Adams, the lead lawyer for the A.C.L.U., said: ''New York City and state law simply does not allow this type of discrimination against lesbian and gay couples.''

In an interview, Mr. Adams added, ''It's safe to say that the vast majority of colleges and universities practice discrimination against gay and lesbian couples.''

Scott Emmons, a professor of molecular genetics at Einstein, said that the medical school's faculty senate has for years supported equal access to housing and other benefits for same-sex domestic partners but that the administration has ignored them.

When, as a member of the Einstein Association of Gays, Lesbians and Bisexuals, he met with the Yeshiva president, Norman Lamm, to discuss the issue, Mr. Emmons said, Dr. Lamm told him that Yeshiva ''will not be on the cutting edge of this issue.''