Objective To describe the incidence of injuries and illnesses sustained during the Tokyo Summer Olympic Games from 23 July to 8 August 2021.

Methods We recorded the daily number of athlete injuries and illnesses (1) through the reporting of all National Olympic Committee (NOC) medical teams and (2) in the polyclinic and medical venues by the Tokyo 2020 medical staff.

Results In total, 11 315 athletes (5423 women, 48%; 5892 men, 52%) from 206 NOCs were followed up prospectively for the occurrence of injury and illness. NOC and Tokyo 2020 medical staff reported 1035 injuries and 438 illnesses, equalling 9.1 injuries and 3.9 illnesses per 100 athletes over the 17-day period. Altogether, 9% of the athletes incurred at least one injury and 4% at least one illness. The incidence of injury was highest in boxing (27%), BMX racing (27%), BMX freestyle (22%), skateboarding (21%), karate (19%) and handball (18%), of which both BMX freestyle and skateboarding were new events, and lowest in diving, road cycling, rowing, marathon swimming and shooting (1–2%). Marathon and artistic swimming presented the highest illness incidences (both 8%), followed by skateboarding and karate (both 7%). In the study period, COVID-19 affected 18 athletes, accounting for 4% of all illnesses and 0.16% of all athletes. Exertional heat illness affected 78 athletes (18% of all illnesses, 0.7% of all athletes), the majority (88%) resulting in no time lost from sport.

Conclusion Overall, 9% of the athletes incurred an injury and 4% an illness during the Games. Comprehensive countermeasures helped mitigate both COVID-19 and exertional heat illnesses.