Olympic athletes experience a high burden of health problems, and health surveillance is fundamental for understanding and preventing injuries, illnesses, and pain. Most surveillance data on Olympic athletes have focused on the Olympic Games, with limited data on injury, illness, and pain patterns outside the Games period. The primary aim of this study was to describe the prevalence, incidence, burden, and patterns of injury and illness, and pain prevalence, among Swedish Olympic athletes over three consecutive years. We conducted prospective weekly health surveillance (April 2022-March 2025) of 225 elite Olympic athletes (51% males; median age 25 years). Health problems were reported using the Oslo Sports Trauma Research Center Questionnaire on Health Problems and diagnosed by the athletes' medical staff. A total of 1441 new health problems were reported (517 injuries, 924 illnesses), with a weekly prevalence of 23.6% (injuries 15.0%; illnesses 9.1%) and an incidence of 4.6 health problems/athlete/year (injuries 1.5; illnesses 3.1). Athletes lost on average 22 training/competition days annually (injuries 8 days; illnesses 14 days). Injury prevalence was similar between sexes and competitive seasons, with the knee (16%), lumbosacral region (14%), and shoulder (10%) being most affected. Illness prevalence was higher in females than in males (11.4% vs 6.9%; prevalence rate ratio (PRR) 1.6, 95% CI 1.4-2.0) and in winter compared with summer sports (11.4% vs 7.9%; PRR 1.4, 95% CI 1.2-1.7). Respiratory illness comprised 78% of cases. Weekly pain prevalence was 44%, with 65% of pain reports occurring without a concurrent reported health problem. One in four Swedish Olympic athletes reported a health problem in an average week, with 4.6 new health problems and 22 time-loss days per athlete per year. Injury and illness patterns varied between subgroups, emphasising the need for targeted prevention strategies to reduce injury and illness burden in Olympic athletes.