BACKGROUND: Mobile applications (apps) are increasingly used in clinical settings, particularly among resident physicians. Apps available to patients and physicians are rapidly expanding. OBJECTIVE: We aimed to describe obstetrics and gynecology (ob-gyn) residents use of and attitudes toward ob-gyn-related mobile apps. METHODS: We conducted a cross-sectional survey of residents at all 19 California ob-gyn programs using a web-based questionnaire. Responses were analyzed using descriptive and chi-square statistics. RESULTS: Of 386 residents contacted, 197 (51%) completed the survey. All respondents owned mobile devices (100% smartphone, 74% tablet), and 93% used apps in the clinical setting. Commonly used ob-gyn-related apps were pregnancy wheels (84%), cervical cancer screening algorithms (68%), and contraceptive eligibility guidelines (47%). Only 53% of respondents recommended apps to patients, with many reporting not being aware of appropriate apps. Sixty-two percent of respondents used apps for learning, but only 3 ob-gyn-specific apps were mentioned. Most chose apps based on recommendations from other residents. Residents viewed mobile technology as an important clinical tool (92%) that improves efficiency (89%). App use did not differ by gender, age, or postgraduate year. CONCLUSIONS: Mobile technology and ob-gyn-related app use are widely used among California ob-gyn residents, who feel that apps enhance their ability to care for patients. Context of app use varies, with most residents using apps during clinical care, but only half recommending apps to patients. Recommendations from other residents are the common resource for discovering new apps, suggesting a need for more formal guidance on finding and evaluating apps.