OBJECTIVE: To assess the correlation of erectile function (EF) and physical activity (PhA) by using standardized, validated instruments in healthy men. METHODS: A urologist examined 674 men aged 45-60 yr at their place of work. That included a urological physical examination, medical history, and assessment of testosterone (T) and sex hormone-binding globulin; all men completed the 5-item International Index of Erectile Function (IIEF-5) as well as the Paffenbarger score. PhA was assessed in kilojoules per week (4.2 kJ=1 kcal). RESULTS: A positive correlation between the IIEF-5 and the Paffenbarger score (r=0.164, p<0.001) was found. The IIEF-5 score increased with an increasing Paffenbarger score up to a level of 4000 kcal/wk. T revealed a trend to a significant impact on the IIEF-5 score, but showed no association with the Paffenbarger score. The risk of severe erectile dysfunction (ED) was decreased by 82.9% for males with PhA of at least 3000 kcal/wk compared with males with PhA under 3000 kcal/wk (OR=0.171, p=0.018). CONCLUSION: Increasing PhA from 1000 to 4000 kcal/wk may reduce the risk of ED.