A federal judge in Alexandria overturned yeaterday the suspensions of 160 J.E.B. Stuart High School seniors who walked out of class Friday in support of higher salaries for Fairfax County teachers.

In his ruling, apparently unprecedented in the county school system, U.S. District Judge Albert V. Bryan Jr. said the students should not have been suspended without a prior hearing.

Bryan ordered school officials to hold hearings for any suspended senior who reports to the school this morning. Individual students could be resuspended afterward.

"I can't see where you can suspend students for five days without a hearing," Bryan told school board attorney Thomas Cawley. "There may be a number of people who had legitimate reasons for not being in school and who may be caught in a general suspension order, and it's those pension order, and it's those persons I'm concerned about."

Bryan's order came in response to a suit filed yesterday by five students, their parents, and by Bobbie Mastrota, president of the Stuart Parent-Teacher-Student Association. The group contended the students' 14th Amendment right to due process was violated by the school's action.

Mastrota said last night she was pleased by the ruling but concerned that following today's hearings, school officials would issue the same suspensions the judge had revoked. But she encouraged students, including her son Michael, one of the suspended seniors, to report to class today.

Stuart Principal Richard W. Johnson, who ordered the suspensions that took effect Monday, said the school was prepared to begin hearings today for all seniors who reported.

An estimated 700 to 750 students participated in Friday's walkout. Johnson said he suspended the seniors as quickly as possible so that they could return to school next week and complete final exams before graduation, which is scheduled for June 8.

Johnson said he had planned to give five-day suspensions effective next Monday to underclassmen who had walked out. But under Bryan's ruling, which took the form of a temporary restraining order against Johnson and county school officials, those students also will be entitled to a hearing before suspended.

The five-day suspension policy for walkouts was announced earlier this spring by the county school administration, which feared the protests would disrupt classes. It is not known what impact Bryan's ruling would have on students at other Fairfax schools who received suspensions earlier for similar demonstrations.

Fairfax school rules provide a process for appealing suspensions to the principal, the area school superintendent, and ultimately to the school board. But Mastrota and other parents complained that Johnson and area superintendent Joseph King had discouraged appeals by Pointing out that the process could stretch into next week and result in some seniors not being able to attend graduation.

Johnson acknowledged he had discussed that possibility with parents. "It was not a threat," he said. "I just felt I had a responsibility to make sure they had all the facts before they made a decision."

Earlier yesterday, Johnson and King had attempted to compromise by shortening the suspensions to three days, provided each senior write an essay about the walkout. But the compromise came too late to prevent the judge's ruling.

Friday's walkout, the largest of a half dozen protests in county schools this spring, followed a Thursday night school board meeting at which the board struck by a decision to hold teacher salary increases to 5.15 percent.