Determining the self-efficacy perceptions of obstructive sleep apnea (OSA) patients has a key role in health care practices. With further evaluation, the Self-Efficacy Measure for Sleep Apnea (SEMSA) could serve as a useful scale to develop specific interventions to increase self-efficacy in patients with OSA during the acceptance and maintenance of continuous positive airway pressure (CPAP) therapy. The aim of this study is to translate the SEMSA into Turkish and to evaluate the psychometric properties of the translation. This cross-sectional study was carried out with a sample of patients recently diagnosed with CPAP-naïve OSA. Linguistic and content validity of the scale were evaluated, while exploratory factor analysis and 2-level confirmatory factor analysis were used for validity. Internal consistency and test-retest methods were used in reliability analyses. The mean (SD) age of the patients with OSA was 51.36 (11.29), and 68% were male. The item factor loads obtained as a result of the confirmatory factor analysis ranged from 0.44 to 0.94, confirming the three-factor structure of the instrument. The Cronbach's α coefficient of the scale was found to be 0.90. Measurements made within the scope of test-retest analysis were found to be related and consistent results were obtained in the intervening time (P < .01). In this study, the Turkish version of SEMSA was found to be a valid and reliable tool and it could be used to evaluate the adherence-related cognition in Turkish patients with OSA on CPAP therapy.