After an absence of 17 years, the Reserve Officers Training Corps has returned to George Washington University this fall, with its flag at one of the busiest corners on campus and no protesters in sight.

"Being in the military has become honorable again," said Stu Merrell, a freshman from Damascus, Md., who belongs to the new Navy training unit.

"I think the Vietnam era has pretty much passed."

The last time George Washington had ROTC was in 1967 when an Air Force unit quietly withdrew because of low enrollment. For several years afterward the university was a center of student ferment against the Vietnam War, with its campus a prime staging area for massive demonstrations.

The return of ROTC to George Washington is part of a nationwide upsurge in enrollments and respectability.

The number of college students involved in its programs is expected to reach about 120,000 this year nationwide -- up about 20 percent over the past three years and about double from the low point in 1974.

Junior ROTC programs also are flourishing at high schools around the Washington area and across the country.

Last week, with the Navy Band playing "Anchors Aweigh," 73 midshipmen marched in dress uniforms for the commissioning of the new George Washington unit as other students and faculty applauded.

"The ceremony that we are having could not have been held on this campus 15 years ago," university marshal Robert G. Jones told an audience of about 250 in the Marvin Theater, about a half block away from the unit's headquarters at 21st and H streets NW. "It is not just the important guests inside the hall but the absence of people outside that makes this ceremony notable."

Among those praising the new cadets was student body president Robert Guarasci. "It certainly is different to see uniformed students walking around the campus here," he said. "I think it's great. . . . The military are a meaningful and useful part of our society."

The ROTC students say they are attracted partly by the scholarships the services offer to help meet the high cost of college, but also by the military's careers and sense of purpose and by patriotism. About 20 percent of ROTC students around the country are women.

"At first it was mainly a way to get money for college," said Elizabeth Blodgett, a GW freshman from Fredericksburg, Va. "Now I think I love it. You're training yourself a certain way and you get a certain amount of self-respect. You know you are doing something important at an early age, which most of the students don't feel."

"You can load a lot of cliches into it, but it's true: the military is there to protect our country," said Merrell, who served as a Navy enlisted man before joining the ROTC program in the hope of becoming a pilot. "It's not just a job like working in a liquor store. Sure, we're going to take care of ourselves and our families, but we're doing more, a lot more."

The new unit at George Washington is the only Navy ROTC group in the Washington area; about 40 percent of its students come from six nearby universities. There is an Army ROTC unit at Georgetown and an Air Force unit at the University of Maryland. Howard University has both Army and Air Force ROTC.

All the units accept students from other colleges, and officials say enrollment in all of them has risen substantially in recent years. For example, the Army unit at Howard has grown by about 100 since 1982, with 273 students now on its roster.

The only local school at which ROTC has encountered significant opposition recently is Georgetown, which is the only college in the area that does not grant academic credit for ROTC courses.

The program's leading foe on the Georgetown campus has been the Rev. Richard T. McSorley, an assistant professor of theology. McSorley said ROTC "shouldn't be here because they just teach to kill." He added that its courses are "counterfeit education," taught by officers "controlled by the Pentagon" instead of by instructors hired and evaluated by the university.

More students are enrolling, McSorley said, because "it's harder for people to pay their way through college, and the military has the money."

However, George Washington University President Lloyd H. Elliott said it was an "honor" to have ROTC at his college both as an opportunity for students and to serve the national defense. GW engineering Dean Harold Liebowitz said military science courses are equivalent in rigor to many others at the university and noted that the officers who teach them must be approved by university officials.

This year 28 of the 73 students in ROTC at GW are benefiting from four-year, full-tuition Navy scholarships, awarded through nationwide competition. Their average combined score on the Scholastic Aptitude Test is about 1,250 -- about 150 points higher than the average for all the college's undergraduates.

"It's very attractive to any institution to bring aboard a nice group of people who have such high SATs," said GW Vice President Charles H. Diehl. "We approached the Navy to request the ROTC unit , and we feel kind of proud that we succeeded in getting it."

The Navy added ROTC units this fall at four universities, bringing its total to 63, compared to 314 campuses with Army ROTC units and 151 with Air Force programs.

According to Pentagon figures, about half of the students who received full-tuition ROTC scholarships in recent years dropped out of the program before they became juniors, avoiding any obligation to serve in the military or pay back the U.S. Treasury. Last fall the rules were changed to permit only freshmen with scholarships to quit without penalty. Pentagon officials say this has cut the attrition rate significantly, though complete data are not yet available.

The scholarship students who quit ROTC after their freshman year must serve two years in the enlisted ranks of the military. Those who complete the program serve a minimum of four years as officers.

Across the country about three-quarters of the Navy ROTC stu- "There's been a change in the whole climate, and we're part of that." -- Capt. Gordon E. Fisher dents have full-tuition scholarships. In the larger Army and Air Force programs about 35 percent have them.

The nonscholarship students get no aid as freshmen and sophomores, but they receive a $1,000 annual "subsistence allowance" as juniors and seniors plus pay for summer training.

"Of course, people see the advantages of the financial aid we offer," said Col. Robert L. Dinkins, head of the Army military science program at Howard. "And we're getting out more and telling them about it. But there's also a much more positive environment now about about the military."

Besides the antimilitary feeling spawned by the Vietnam War, another factor in the decline in ROTC enrollment was the end of the draft in 1973, several military officials said. Before the draft ended, ROTC often was seen as an attractive way to meet a military obligation because it meant entering the service as an officer.

During the past few years, however, the military services have developed as volunteer forces, meeting their manpower quotas, raising the quality of enlistees and attracting record numbers of applicants to the military academies as well as boosting enrollments in ROTC.

"There's been a change in the whole climate," said Capt. Gordon E. Fisher, head of the George Washington ROTC unit, "and we're part of that."

James Taylor, a University of Maryland sophomore who belongs to the unit, said that when his father taught naval science in the late 1960s, ROTC students made it a point never to walk on campus alone. Now, Taylor said, he wears a uniform two days a week and often gets friendly questions.

"I don't feel there's any resentment," he said. "It's wonderful."