This study was supported in part by the School of Health Related Professions Research and Development Fund, University of Pittsburgh, Pittsburgh, PA A common complaint of competitive swimmers is shoulder pain. The purposes of this study were to: 1) provide normative data on shoulder flexibility in swimmers, 2) determine if a correlation exists between flexibility and shoulder pain, and 3) determine the correlation between strength and endurance ratios to shoulder pain. The subjects were 28 Division I collegiate swimmers and four club swimmers. Shoulder flexibility measurements were obtained bilaterally using a universal goniometer. Strength and endurance ratios were obtained bilaterally using the Cybex II(R) isokinetic dynamometer and the Upper Body Exercise Table(R). The swimmers completed a questionnaire that included a shoulder pain performance scale. The Pearson product moment correlation coefficient and multiple regression (R) analysis were the applied statistics. The results demonstrated that no significant correlation (p > 0.001) existed between shoulder flexibility, strength ratios, and shoulder pain. There was a significant (p </= 0.001) negative Pearson's correlation between endurance ratios of external rotation, abduction, and shoulder pain in competitive swimmers. A multiple R of 0.78 was obtained for the combination of external rotation and abduction endurance ratios to shoulder pain, which was significant (p </= 0.001). Clinical implications suggest that when evaluating swimmers, clinicians need to be aware of the importance of assessing the endurance ratios of the shoulder abductors and the external rotators at faster speeds. With decreased endurance ratios, competitive swimmers may be more likely to develop shoulder pain. J Orthop Sports Phys Ther 1992;16(6):262-268.