U OBJECTIVE: To investigate whether the proportion of running-related knee injuries differed in normal-weight, overweight, and obese runners. U DESIGN: Comparative study. U METHODS: Data from 4 independent prospective studies were merged (2612 participants). The proportion of running-related knee injuries out of the total number of running-related injuries was calculated for normal-weight, overweight, and obese runners, respectively. The measure of association was absolute difference in proportion of running-related knee injuries with normal-weight runners as the reference group. U RESULTS: A total of 571 runners sustained a running-related injury (181 running-related knee injuries and 390 running-related injuries in other anatomical locations). The proportion of running-related knee injuries was 13% lower (95% confidence interval: –22%, –5%; P = .001) among overweight runners compared with normal-weight runners. Similarly, the proportion of running-related knee injuries was 12% lower (95% confidence interval: –23%, –1%; P = .042) among obese runners compared with normal-weight runners. U CONCLUSION: Overweight and obese runners had a lower proportion of running-related knee injuries than normal-weight runners.