Valgus extension overload is well described in the throwing athlete. The surgical treatment involves posterior olecranon osteophyte resection. It is not known how much of the posterior olecranon can be resected before increased stress is placed on the ulnar collateral ligament. Ten cadaveric arms underwent posterior olecranon resection in 4-mm increments. After each bone resection, three different valgus loads were applied to the elbow at 70 degrees and 90 degrees of flexion. Ulnar collateral ligament strain significantly increased with each load. Significantly more strain occurred on the ulnar collateral ligament at 90 degrees compared with 70 degrees of elbow flexion. This difference may be the result of the relative importance of the ulnar collateral ligament and the posterior olecranon at different positions of elbow flexion. The strain on the ulnar collateral ligament was slightly higher after the 8-mm and 12-mm cuts but not statistically significant. This study suggests that at moderate quasistatic valgus loads, ulnar collateral ligament strain is not significantly increased with posterior olecranon resection.