OBJECTIVES: To determine the effects of sporting activity on absenteeism in a working population. METHODS: Data were used from a prospective cohort study in a working population with a follow up period of 3 years and were collected with yearly questionnaires or collected from company records. Complete data on absenteeism, sporting activity, and potential confounders were collected for 1228 workers. ANOVA was used to test differences in frequency and duration of absenteeism, correlations were computed to measure the association between number of sporting years (divided by age) and frequency and duration of absenteeism, and survival analysis, according to the Cox proportional hazards model, was used to test differences in relative risk at absenteeism and recovery. All analyses were adjusted for age, gender, smoking, and alcohol consumption, and were stratified for employees with sedentary and with more active jobs. RESULTS: ANOVA showed a statistically significant higher mean duration of absenteeism among employees not practicing sports, of approximately 20 days over a period of 4 years. The survival analysis showed an increased relative risk at absenteeism (relative risk (RR) 1.09; confidence interval (CI) 1.01 to 1.18) and a decreased relative risk at recovery (RR 0.90; CI 0.85 to 0.95) for employees not practicing sports. The effect of sporting activity is larger in employees with sedentary work. No associations were found between number of sporting years and absenteeism. CONCLUSION: Employees practicing sports take sick leave significantly less often than their colleagues not practicing sports, while their periods of sick leave are shorter, especially when their work is sedentary.