© 2020 Sports Medicine Australia Objectives: Understanding the differences in baseball pitching biomechanics between American and Japanese pitchers may help with training and developing these athletes. The purpose of this study was to investigate the kinematic and kinetic differences in collegiate baseball pitchers from United States of American and Japan. Design: Controlled laboratory study. Methods: Data were analyzed for 11 American and 11 Japanese collegiate pitchers throwing fastballs using 3D motion capture (480 Hz). Results: The Americans were heavier (95 ± 7 kg vs 81 ± 7 kg), taller (189 ± 3 cm vs 180 ± 6 cm), and had faster ball velocity (39 ± 1 m/s vs 35 ± 2 m/s). By the end of arm cocking phase, the American pitchers had rotated their shoulder to a greater degree (p = 0.021, d = 1.5) and at ball release the Japanese had greater knee flexion (p = 0.020, d = 1.2). American pitchers exhibited greater peak kinetics on the throwing arm; however, when normalized for height and weight only three differences remained. Conclusion: The differences found between the American and Japanese players could contribute to the increased ball velocity in the American pitchers. Additionally, throwing arm peak kinetics were greater in the American pitchers which may help generate greater ball velocity; however, increased kinetics may also lead to increased risk of injury.