Local clinics that offer blood tests to determine exposure to AIDS virus are reporting a large increase in business because people outside the risk groups -- some with virtually no risk of exposure -- are asking to be tested, according to clinic directors.

Because of increased demand, the testing site in Montgomery County expanded this month to three days each week instead of one.

At the Whitman-Walker Clinic in the District, the best known of the five test sites in the metropolitan area, up to 65 people have been turned away on each of the last three Wednesday night testing sessions, according to Jason Whiddon, coordinator for the clinic's program to test for the HTLV-III virus. The clinic, which was seeing an average of just 15 persons a week when testing began three months ago, can only handle tests for a maximum of 50 people each session.

"It's a lot of new people outside of the risk groups," said Whiddon. "There's a fair number of married people who worry that their occasional indiscretions will be passed on to their wives . . . . There are a lot of people who would not consider themselves gay, but occasionally have homosexual contacts."

Dr. Fred Payne, director of communicable diseases at the Fairfax County Health Department, said the "substantial" increase in appointments for the test in the last month can be credited to increased press coverage of the disease and actor Rock Hudson's AIDS illness.

The results of many of those tested recently have been negative. Some, including a woman who asked for the test because she ate dinner at the home of a neighbor with a homosexual son, have had little reason for the test.

"But the process is educational," said Whiddon, who said the clinic has "relaxed" its initial policy of discouraging people from taking the test as long as they understand the test does not diagnose AIDS and only a small percentage of those with positive tests will develop the disease. "Hopefully, people will feel better about themselves and being around people with AIDS. It's a service to end some of the unfounded fears."

Some of those seeking testing include hair transplant patients , he said. Another was asked by his dentist to obtain test results.

"I've had a fair number of people come in who are military and who want to know first before the military requires it," Whiddon said.

The Department of Defense now requires all recruits to be tested for the virus and is expected to announce its decision shortly on whether to consider testing for all active duty personnel.

Harvey Friedman, a D.C. attorney who specializes in military law and the gay community, said his past cases show that servicemen found to have AIDS are "drummed out immediately" despite the assurances of military officials that this isn't done.

At the testing site at the District's Southwest Health Clinic, a former drug user said his girlfriend demanded he be tested, according to a clinic staff member. Others, who are not members of risk groups and insist on written proof of their results, may have been asked by their employers to be tested, the staff member theorized.

The tests at all centers are confidental and anonymous, with numbers used instead of names. Those seeking the test are counseled.

There are two testing sites in the District, one in Silver Spring, one in Cheverly and one in Fairfax. All began operating in late May or early June under special 90-day funding from the federal government, which has been extended until mid-October at many centers.

Most of the tests are performed for free, but Whitman-Walker, which no longer receives the test kits free from the D.C. government because of budget problems, asks for a $15 donation.

"We don't want to be flooded with people who don't need the test," said Whiddon. "Basically, if you haven't had any kind of intimate contact with those who are at high-risk, your chance of exposure is practically nothing and you don't need this test."

Those at high-risk include intraveneous drug abusers, homosexual men and hemophiliacs.

Testing sites include:

Montgomery County: 2000 Dennis Ave., Silver Spring. By appointment only. 593-8507.

Prince George's County: Cheverly Health Center, P.G. General Hospital grounds, Landover Road, Cheverly. By appointment only. 386-0110.

District of Columbia: Whitman-Walker Clinic, 2335 18th St. NW, walk-in Wednesday evenings, 332-5939; Southwest Health Center, 850 Delaware Ave. SW, walk-in. 727-3611.

Northern Virginia: Joseph Willard Health Center, 3750 Old Lee Highway, Fairfax. By appointment only. 569-6704.