Comparative analysis of injury and illness prevalence in elite and amateur athletes provides the basis for the development of tailored prevention programs. The authors analyzed the differences in frequency and characteristics of injuries and illnesses which occurred in elite and amateur athletes during the 2019 Gwangju Federation Internationale de Natation (FINA) and Masters World Championships. The 2019 FINA World Championships hosted 3095 athletes in the disciplines of swimming, diving, high diving, artistic swimming, water polo, and open water swimming. While the 2019 Masters World Championships hosted 4032 athletes in swimming, diving, artistic swimming, water polo, and open water swimming. All medical records were electrically recorded in every venue as well as the central medical center located at the athlete’s village. More elite athletes visited clinics than amateur athletes during the events (15.0 vs 8.6%, p＜0.05) despite the ages of amateur athletes being higher than elite athletes (41.0±15.0 vs 22.4±5.6 years, p＜0.01). Elite athletes complained mainly of musculoskeletal problems (69%), while amateur athletes complained of both musculoskeletal (38%) and cardiovascular (8%) problems. The most frequent injury in elite athletes was due to overuse in the shoulder joints, wh...