The University of Maryland will change its drug-testing procedures in September to prevent the possibility of cheating, Jim Dietsch, who oversees the procedure for the athletic department, said yesterday.

Under current testing procedures, athletes are monitored but sometimes are not accompanied when they give their urine samples, said Dietsch, who said he now realizes there is potential for an athlete to substitute a different urine sample.

The change was discussed in a meeting with athletic officials and representatives from the campus health services unit this spring, Dietsch said, and is not in response to the cocaine-related death of basketball star Len Bias on June 19. The concern arose, Dietsch said, in April and May after athletic department officials heard "rumors" that tests could be circumvented by substituting urine.

Maryland initiated mandatory drug testing for all athletes last September.

"It's our first year, and we've initiated ourselves," he said. "We've learned some things and we're going to tighten up the testing. . . . We said, yeah, we've heard these rumors about urine being substituted , and decided how we should react."

Athletes are tested for drugs when they take their annual physicals, and then are subject to random testing, or spot checks, over the course of the season, said Dietsch, who is the athletic department's academic coordinator. The number of tests varies from athlete to athlete, he said. If an athlete tests positive in either a physical or random test, he or she is retested, usually within the week, at the health services center, he said.

Dietsch confirmed that some Maryland athletes had received positive results from first tests, but said no one had tested positive a second time. The test results are kept confidential by the health services department. The athletic department has requested the number of positive results, but has not yet received them, Dietsch said.

"All we were ever told was that the numbers were low," he said. "We have requested the number, not the names."

Health services officials have declined to comment on the subject.

Under the new measures, athletes will be required either to strip when giving the test to prevent concealing any samples, or they will be accompanied and watched while they take the tests, Dietsch said.

"It will probably be some combination of the two," he said. "They will either strip down completely, or someone will be with them when they're giving the sample."

Although some football players are taking physicals this week, Dietsch said that they, as well as all other athletes, will be tested again in the fall under the new guidelines.

Upperclassmen on the women's basketball team also are being tested now, and will be retested in the fall, Dietsch said.

Under Maryland's drug guidelines, if an athlete tests positive, he or she is retested to confirm the result. If that also is positive, the athlete is placed in a mandatory drug counseling program administered by health services. An additional positive result would bring a two-week suspension from practice and competition. One more would result in the player being dismissed from the team, moved out of athletic housing, and forfeiting the scholarship at the end of the academic year.

Dietsch said Maryland officials see particular need to improve the drug testing done during physicals. Athletes sometimes have up to four weeks' notice before the physical and testing, and he said this will be changed.

"We won't tell them exactly when they're going to be tested," he said.

In random testing, a schedule is drawn up by the health services and athletic departments corresponding to the athletic seasons. In addition, a coach may request that a certain athlete be tested at any time.

Dietsch said random tests probably are the strongest phase of Maryland's testing. They usually are performed in the training room for basketball players and in the locker room for football players. The players are given a bottle with a label on it, which they initial when they are finished.

But Dietsch also said that the administering of the random tests varies.

He said he usually accompanies athletes as they take the tests in the locker room. Other times, the athletes go to a stall, but Dietsch said sometimes players go into a closed bathroom to take the test.

"Most of the random tests are done in a locker room setting," he said. "If they are coming off the field or the court in their uniform and you get them before they get to the locker room or the shower, then they can't get to their clothing or a bag and so forth.

"So I feel the random tests are fairly accurate. It would be very hard to get through an entire practice with it a urine sample from someone else on you."

Dietsch said members of the women's basketball team are not accompanied when they take the test, but are allowed to go into a bathroom and close the door.

In addition, the women have not been randomly tested often, according to one member of the team, who said three players were given spot tests "at the end of last season, but that was it."

Despite the changes that will take place in the fall, Dietsch said he felt reasonably sure of the integrity of Maryland's tests.

"I feel confident that it would be hard to cheat," he said. " . . . Maybe there's some doubt that they're 100 percent. But they're 95 percent sure."

Gertie Lewis, whose son Derrick is a member of the basketball team, said yesterday that parents had not written Coach Lefty Driesell twice out of concern over their sons' academic performances. She said they signed "a piece of paper, but it was not given to Coach Driesell and it will not be given to Coach Driesell." It was reported Lewis and other parents had signed two letters expressing such concerns.