The Supreme Court yesterday upheld regulations aimed at limiting the number of people eligible for Social Security disability benefits, saying the regulations could be applied to screen out applicants who do not have severe medical problems.

The justices voted 6 to 3 to reject arguments by groups representing the disabled, who said the regulations improperly denied benefits because they relied only on medical data and excluded consideration of an applicant's age, education and work experience. The groups were joined by 29 states.

The regulations have allowed officials to reject hundreds of thousands of the more than 2 million claims filed each year. But the practical effect of yesterday's decision was uncertain, as new guidelines have been issued and because the justices did not rule on whether administration officials had used the regulations improperly.

In other action yesterday, the court:

Agreed to decide next year whether federal courts may review Central Intelligence Agency decisions to fire employes. The justices said they would hear the CIA's appeal of a ruling involving a homosexual electronics technician.

The employe, identified only as John Doe, voluntarily told an agency security officer in 1982 that he was a homosexual. He was later told that he was a "security threat," but given no further explanation for his firing. A divided three-judge appeals court panel here last August rejected the government's arguments that the National Security Act of 1947 did not allow courts to review the CIA's actions. The case is Webster v. Doe.

Turned down an appeal by a Virginia man who wanted the justices to let him to use a license tag "ATH-EST. The court, without comment, refused Arnold M. Via, of Grottoes, Va., who had argued that the Department of Motor Vehicles' decision not to let him use the tag violated his constitutional freedoms of speech and religion.

Refused a request by U.S. Customs Service employes to speed consideration of their appeal of a lower court ruling that allowed mandatory drug testing of some employes. As a result, even if they decide to review the ruling, the justices will not render a decision until next year.

The Social Security case, Bowen v. Yuckert, had been closely watched because the disability regulations, issued in 1978, had been used to refuse a record number of applicants. Before the regulations, about 8 percent of the 2 million yearly claims had been turned down because the applicants' medical disabilities were not sufficiently severe.

After the regulations went into effect, about 40 percent, or 800,000 claims, were rejected on "nonseverity grounds."

The rate fell back to 25 percent after all 11 regional federal appeals courts either stopped the administration from using the regulations or limited their use.

Justice Lewis F. Powell Jr., writing for the majority, said the regulations were in keeping with congressional intent to ensure that disability benefits go only to those with medical impairments.

The screening regulations, he said, help "increase the efficiency and reliability of the evaluation process by identifying at an early stage those claimants whose medical impairments are so slight that it is unlikely they would be found to be disabled even if their age, education and experience were taken into account."

But Powell, in a footnote, said the court was rejecting only a theoretical challenge to the regulations and was not addressing whether they had been improperly used. He was joined by Chief Justice William H. Rehnquist and Justices Byron R. White, Sandra Day O'Connor, John Paul Stevens and Antonin Scalia.

Justice Harry A. Blackmun, joined by Justices William J. Brennan Jr. and Thurgood Marshall, dissented, saying the regulation conflicted with what Congress intended and it was "highly inappropriate for this court to permit the secretary to continue to enforce" them.

O'Connor, joined by Stevens in a separate concurring opinion, said she was concerned that otherwise eligible applicants might be denied benefits by the way the administration had been using the regulations.