Clemson said 23 football players have tested positive for coronavirus since returning to campus this month.
Clemson announced the results Friday. It did not identify the athletes.
In all, school spokesman Jeff Kallin said 28 people were found with COVID-19 since testing began for athletes and other personnel on June 8.
The uptick at Clemson mirrors one in the state of South Carolina, which reported a single-day high of 1,081 people testing positive on Friday.
Along with the players, two football staffers and three athletes from other sports were found with the virus.
The school said all were asymptomatic and have begun isolation for at least 10 days. No one has been hospitalized.
Those who've been in contact with people testing positive have been asked to self-quarantine for at least two weeks.
In all, Clemson has administered 315 tests for the disease since athletes came back to athletic facilities.