The purpose of this study was to investigate the shoulder strength ratios obtained from college-level baseball pitchers and age- and sex-matched nonpitchers. Shoulder flexion/extension and externallinternal rotation strength ratios were assessed in 10 pitchers and 9 nonpitchers. Speeds selected for testing were 180 and 300 degrees /sec on the Cybex /I.@R esults indicated that both pitchers and nonpitchers generated greater peak torque values for the extensors and internal rotators than for the flexors and external rotators of the shoulder. A comparison of shoulder strength ratios between a pitcher's throwing arm and his nonthrowing arm was statistically significant (p < 0.05) for shoulder external/internal rotation at the speeds of 180 and 300 "/set. A comparison of shoulder strength ratios between pitchers and nonpitchers on the nondominant arm was not statistically significant for any of the speeds or directions tested. A comparison of the shoulder strength ratios between pitchers and nonpitchers on the dominant arm was statistically significant (p < 0.05) for all directions and speeds tested. The relationship between shoulder muscle imbalance and injury was discussed. J Orthop Sports Phys Ther 1987;8(9):451-461.