The number of foreign graduate students applying to study in the United States has declined since last year, according to survey results that are scheduled to be released today. The decline is being attributed to national-security policies that have made foreign students feel unwelcome.

The survey found that the decline is particularly acute at 25 leading research institutions that enroll the most international students. Fifteen of those top-25 institutions reported a drop of more than 10 percent in foreign applications from last year to this year, with the largest decline coming among Chinese students. Four of the colleges reported decreases of 50 percent or more in Chinese applicants.

More than 530 colleges responded to the survey, which was conducted this month by five higher-education associations. The results show that the United States "is a less desirable location for the world's best," said Terry W. Hartle, senior vice president for government and public affairs at the American Council on Education, one of the five associations.

The other groups were the Association of American Universities, the Council of Graduate Schools, Nafsa: Association of International Educators, and the National Association of State Universities and Land-Grant Colleges.

"This is an unfortunate by-product of the necessary effort to enhance national security," Mr. Hartle said. "National security is clearly the pre-eminent priority, but it's not the only priority."

The associations that conducted the survey said the results suggest that foreign students view the United States as unwelcoming, largely because of the difficulty they face in securing visas.

Following the terrorist attacks of September 11, 2001, the federal government put in a place a new computerized system to track international students and professors. The system -- known as Sevis, or the Student and Exchange Visitor Information System -- has been plagued with technical bugs, and many colleges have blamed it for delays in their students' getting visas.

"For decades, we have seen a steady increase in international students," Mr. Hartle said, "so a decline is troubling."

Among the survey's findings:

Nearly half, 47 percent, of the 250 institutions that provided data regarding prospective graduate students reported a decline in international applicants. Only 14 percent reported an increase.

Of the 382 institutions that supplied information on undergraduate applicants, 36 percent reported a decline among prospective international students.

Almost half, 48 percent, of the 216 institutions that provided data on Chinese graduate students reported a decline in applications.

In issuing the survey, the five higher-education associations urged Congress to change the visa-processing system so that it would not only deny visas to "those who would do harm," but also welcome "legitimate visitors." Such a system, the groups said, must include giving the necessary federal funds to agencies in charge of visa policy, providing expeditious service to applicants who present no special risk, and creating a more predictable visa process.