OBJECTIVE To identify predictors potentially contributing to patients' nonattendance or to same-day cancellation of scheduled appointments at an adult endocrinology office practice. METHODS A retrospective, records-based, cross-sectional study was conducted using data from 9,305 electronic medical records of patients presenting at a U.S. metropolitan adult endocrinology clinic in 2013. Statistical analyses included multivariate regression, calculated odds ratios, and posttest probabilities. RESULTS Of 29,178 total patient visits analyzed, 68% were attended by patients. Of total scheduled appointments, 7% resulted in nonattendance and 5% in same-day cancellation. The most significant predictors of nonatten-dance were a previous history of nonattendance (P<.001), uncontrolled diabetes (P<.001), and new patients to the practice (P<.001). Long lead-time to appointment (P = .001), younger age (P<.001), and certain insurance carriers (P<.001) also were significant predictors. CONCLUSIONS Specific predictors of nonattendance at scheduled appointments were identified using statistical analysis of electronic medical record data. Previous history of nonattendance and having uncontrolled diabetes (especially in patients newly referred to the practice) are among these significant predictors. Identifying specific predictors for nonattendance enables targeted strategies to be developed. BACKGROUND APRN = Advanced Practice Registered Nurse CI = confidence interval DM = diabetes mellitus EMR = electronic medical record HbA1c = glycated hemoglobin NS = no-show OR = odds ratio SDC = same-day cancellation.