BOSTON (AP) _ Nervous about traveling overseas during wartime, some high school and college students are dropping plans to study abroad.

A few returned early from foreign study programs, while others called off travel plans. Parents and students unsure what to do are deluging administrators with anxious inquiries.

''They're mainly looking for information, particularly any threats of terrorism,'' said Harvard University spokesman Peter Costa. ''We try to knock down all the rumors and still express our concern that these are perilous times.''

Their worries aren't unwarranted. The State Department is urging Americans to curtail travel to certain parts of the world to avoid terrorist attacks.

''The war has the potential for far-reaching effects all across the world,'' said Nancy Kelly, foreign studies advisor at Tufts University in Medford.

The terrorist bombing of Pan Am Flight 103 over Scotland in December 1988 remains fresh in many people's minds. Thirty-five college students, 25 from Syracuse University, were among those killed.

So far, though, only a few overseas programs have been canceled, mostly Italian-operated programs in Florence and Rome.

''The threat was made against American students in Italy should the U.S. attack Iraq,'' said Joanne Picard, assistant dean of international affairs at Mount Holyoke College. ''It was generally believed to be a hoax, but authorities were taking it very seriously, especially since over the years there has been a fair amount of terrorism in Italy.''

Most other programs are expected to continue as scheduled.

''The State Department is not saying 'do not travel,' they're saying 'Use caution when traveling,''' said Barbara Smalley, an associate director at the Council for International Education Exchanges in New York City. ''It's an individual decision.''

So far, most college students have decided to stick with their original plans. At Boston University, only three or four of 400 students scheduled to depart for overseas study decided not to go.

''Probably another three or four or five have come home,'' said Tim Perkins, the school's assistant vice president for international programs. ''In a regular term, at least that many panic or get homesick or get culture shock and come home.''

Many schools were most concerned about visitors to Israel, now the target of Iraqi missile attacks.

''I don't think we have any more students in Israel,'' said Kelly, of Tufts. ''Those who were there returned, and those who were planning to go didn't.''

Because of fears about terrorism, enrollments have dipped slightly even in areas not directly affected by the war.

At Emerson College, 11 of 50 students scheduled to spend the semester at a 12th-century castle in the Netherlands decided to stay home. Two backed out as the group boarded its flight earlier this week.

''Many of them were anxious about their vulnerability, even though we tried to assure them that our safeguards there are at least equal to those they experience in Boston,'' said Larry Conner, Emerson associate vice president.

CIEE, which arranges student tours nationwide, reported that 17 of 164 students scheduled to study in France or Spain this spring have withdrawn because of the war.

Of 225 students currently in Spain, ''six are returning earlier than expected,'' Smalley said.

For the majority continuing on with overseas study, advisors have stepped up instructions on keeping a low profile in countries where anti-American sentiment may run high.

''Basically, one does not go around flaunting the fact that you're an American, flashing an American passport or engaging in political conversations in areas that are public,'' said Robert Vozzella, director of international cooperative ecucation at Northeastern University.

At the high school level, many school boards are calling off long-awaited tours. In New Hampshire, students from Berlin, Gorham and Stratford dropped plans for a 10-day visit to France and Great Britain next month.

Several schools on Boston's South Shore have canceled trips to Spain and France that had been scheduled as far ahead as July.

Ellen Lautz, CIEE's manager of secondary education programs, said some school boards have even postponed class trips to Washington, D.C., because of concerns about terrorist attacks.