For the first time in the history of the Pan American Games, the United States failed to win the men's discus throw today. The United States, of course, had no entries, since both Paul Bishop and Greg McSeveney flew home Tuesday in the wake of the drug-testing scare.

So Luis Delis won virtually unopposed, at 220 feet 10, and brought Cuba its sixth gold medal in nine men's track and field events contested thus far. The United States has won none.

At least, the U.S. women have managed to conduct a few renditions of "The Star-Spangled Banner." Coleen Sommer won the high jump today at 6-3 1/4 and Joan Benoit took the 3,000 meters in 9:14.19 to give the United States three golds in five women's events.

The U.S. women, outdoing their male counterparts, also won a gold medal in basketball, one in tennis and one in table tennis as the U.S. raised its medal count to 104 golds and 214 overall. Cuba was second at 64 golds and a total of 135.

But the U.S. men got a surprise boost late tonight when pole vaulter Mike Tully came back to compete. He had left Tuesday, one of a dozen track-team members who returned home after news of the drug crackdown spread.

Sommer and Benoit hardly were accepting bows. Neither performed very well or had much competition. The high jump had only five entries; only two cleared more than six feet.

"I came here instead of staying in Europe because I thought I'd get more recognition . . . and that's important with the Olympics coming up," Sommer said. "But it really isn't very good competition.

"I think I might have gone higher if somebody else was left. But I had problems with the crowd and with the officials.

"The crowd made all kinds of noise while we were getting ready to jump. Maybe that's their way of being supportive, but it's not ours."

Benoit beat teammate Brenda Webb by 100 yards and third-place Monica Regonesi of Chile finished a half-lap back. Laverne Bryan of Antigua collapsed after four laps and was carried off on a stretcher.

Conceicao Geremias of Brazil edged Cindy Greiner of the United States for the heptathlon title by 16 points with a total of 6,084 points.

In the women's 100-meter hurdles, nine ran for eight berths in the final, with favored Benita Fitzgerald of Dale City, Va., advancing in 13.21.

The U.S. women scored the most lopsided victory of the basketball tournament in winning the Pan Am gold for the fifth time.

Lisa Ingram, the 10th player on the squad, scored 23 points to lead the unbeaten U.S. team in a 113-33 rout of Venezuela.

Tuesday's defections are a major reason for the poor showing of the U.S. men, but another is the low level of the team that was selected. Because of the proximity of the World Championships and the monetary opportunities offered by a trip to Europe, few of the top U.S. athletes agreed to come here. The result has been a mediocre, disappointing competition with few good performances and some fields so thin they are an embarrassment.

The absence of the U.S. shot putters enabled Delis to win that event Tuesday at 59-10 1/4, the first gold-medal performance under 60 feet since 1955. Dave Laut of the United States won at San Juan in 1979 with a throw of 72-10 3/4.

Only five hammer throwers competed in that event Wednesday and Genoveno Morejon of Cuba was able to take first place with 214-5, the poorest winning effort since 1967.

Cuba's Jaime Jefferson won the long jump Wednesday at 26-4 1/4, shortest to take the gold since 1971. Vesco Bradley's 26-2 3/4 was second best among the eight entries.

Frank Monthie of Cuba produced the first U.S. defeat in the 400-meter hurdles since 1963, as he ran 50.02 Wednesday, a relatively slow time. James King, the only U.S. entry, finished third.

Besides the discus, the only men's competition today consisted of semifinals in the 200 meters. The 400-meter quarterfinals were canceled because of lack of entries, announcement of which drew whistles from the crowd.

In baseball, Luis Cano Arauz and Cayetano Garcia damaged U.S. hopes for a gold, leading Nicaragua to a 9-5 victory that stopped the U.S. eight-game winning streak.

Garcia had five RBI, while Cano Arauz blanked the United States on four hits through eight innings. The losers got their runs in the ninth. The U.S. is 8-1 overall.

Michael Jordan's 24 points led the undefeated U.S. men's basketball squad to an 88-68 victory over Argentina. The U.S. wasn't seriously threatened after taking a 35-23 lead. Jordan made 13 of his game-high 24 points in that time. The U.S. men are 6-0 overall and 3-0 in the final round.

Greg Holmes, the NCAA tennis champion from the University of Utah, won a gold beating Fernando Perez Pascal of Mexico, 7-6, 7-6.

Jim Martin, a D.C. fireman who lives in Alexandria, Va., won the gold in the 180.5 pound division of sombo wrestling by defeating Luis Delgado of Venezuela.

Chile's leading cyclist, Fernando Vera, became the latest athlete to be caught in the drug probe. He tested positive for anabolic steroids.