The Senate vote to repeal the 17-year-old "don’t ask, don’t tell" policy against homosexuals serving openly in the armed forces removes a reason that many of the nation’s elite colleges have cited for barring the Reserve Officers Training Corps from recruiting on their campuses.

Already, the presidents of Harvard, Yale and Columbia have issued statements expressing interest in bringing ROTC back. But it is not clear whether there will be enough student interest on those campuses to warrant ROTC’s presence.

ROTC, which has units on 327 U.S. campuses, was sent packing from several Ivy League and other prominent campuses in the late 1960s and early 1970s, in the firestorm of student protests against the Vietnam War. More recently, though, ROTC has faced opposition because of discrimination against gays and lesbians in the military.

Eileen M. Lainez, a Defense Department spokeswoman, said Monday that it would be "premature to speculate" on plans for new ROTC units.

Diane H. Mazur, a law professor at the University of Florida and a former Air Force officer, said she doubted that the military would reinstate ROTC at Ivy League colleges because it is expensive to operate there, particularly for the relatively few number of students likely to be recruited.

"I think the military is much more persuaded by output, is much more persuaded by economic efficiency," Mazur said.

Dr. Drew Faust, the president of Harvard, said over the weekend that she was looking forward to "pursuing discussions with military officials and others to achieve Harvard’s full and formal recognition of ROTC."

Last month, in a joint appearance with Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, who opposed the "don’t ask, don’t tell" policy, Faust said she hoped the policy would end so that Harvard could embrace "both service and inclusion." According to a Harvard spokesman, 19 of its students participate in ROTC at MIT.

President Lee Bollinger of Columbia said the repeal of "don’t ask, don’t tell" would allow the university to fulfill its desire to be more open to the military. In a statement, Bollinger said the repeal "effectively ends what has been a vexing problem for higher education, including at Columbia, given our desire to be open to our military, but not wanting to violate our own core principle against discrimination on the basis of sexual orientation."

The Student Affairs Committee of the Columbia University Senate, a policymaking body of students, faculty, administration, alumni and others, said Monday that it had formed a Task Force on Military Engagement to consider whether the university should formally participate in ROTC.

Before making any decision, the committee said, it would conduct an opinion survey and hold hearings on the issue. The committee’s chairman, Tao Tan, said the process would be driven by students, rather than faculty.

Several Columbia students said this week that while they would not object to the return of ROTC, they did not expect their classmates to show much interest in military careers.

"Most people come here to have a specific career – investment bankers or lawyers," said Alex Gaspard, an 18-year-old who hopes to go to law school.

"Most students here aren’t focused on military service," added Chimezie Ozurumba, a 32-year-old graduate student studying finance .

Columbia has six students enrolled in ROTC programs at nearby schools, according to Robert Hornsby, a university spokesman.

At New York University, where there is no ban on ROTC, students who want to participate go to programs at other campuses, according to John Beckman, a spokesman.

Yale University’s president, Dr. Richard C. Levin, said Monday that the university "is eager to open discussions about expanding opportunities for students interested in military service, and we will be discussing this matter with the faculty of Yale College in the spring semester."

Yale College is the university’s undergraduate division.

Levin acknowledged that although he had asked Yale executives to explore the military’s interest in establishing a ROTC unit at Yale, there was no certainty that the Department of Defense would agree to return to the campus.

Four Yale students now attend ROTC at the University of Connecticut or the University of New Haven, according to Thomas Conroy, a spokesman for Yale.

Brown currently has only one student in the program, through Providence College, according to a spokeswoman. ROTC was phased out in the early 1970s based on academic issues, she said, and any academic issues raised by a return of ROTC would require a faculty vote.

At Stanford, where about 15 students participate in ROTC at nearby campuses, the Faculty Senate’s ad hoc committee on ROTC has for months been considering whether to expand its relationship with ROTC and is scheduled to make a recommendation this spring.

"I’m personally delighted by the repeal, and I do have the feeling it will lighten the task of our committee," said Ewart Thomas, a psychology professor who heads the committee.

But, he said, there may be continued opposition to having ROTC on campus, whether from those who believe the military will still discriminate against gays, or for academic reasons.

When Stanford’s ROTC was shut down in 1973, he said, the stated reason was not the politics of the Vietnam War but rather academic standards: The low-quality intellectual content of ROTC courses, Stanford concluded, did not meet university standards.

"Of course, you have to distinguish between what was said, and the political climate," he said.