Purpose: The purpose of this study is to translate the Penn Shoulder Score into Turkish and to establish its cultural adaptation, reliability, and validity in patients with shoulder dysfunctions. Methods: The Penn Shoulder Score was translated and culturally adapted from English into Turkish. Subsequently, the Penn Shoulder Score, the Constant Score, the American Shoulder and Elbow Score, and the Western Ontario Rotator Cuff Index were completed by 97 patients with shoulder dysfunctions. To determine the test-retest reliability, 30 patients completed the Penn Shoulder Score again on day 3. Intraclass correlation coefficient and Cronbach alpha were calculated to assess reliability. The validity of the questionnaire was assessed in terms of convergent validity with Pearson Correlation Coefficient using the Constant Score, the American Shoulder and Elbow Score, and the Western Ontario Rotator Cuff Index. Results: Internal consistency was good, with a Cronbach alpha of 0.81. The Intraclass correlation coefficient was 0.90 (95% confidence interval: 0.78, 0.90), demonstrating good test-retest reliability. Pearson correlation coefficients of the Penn Shoulder Score in relation with the Constant Score, the American Shoulder and Elbow Score, and the Western Ontario Rotator Cuff Index were 0.65, 0.78, and -0.77, respectively. Conclusion: The Turkish version of the Penn Shoulder Score is a reliable and valid measure for assessing patients with shoulder dysfunctions.