Epilepsy is the most common serious neurological disorder in the United States, but little is known about its effect in the perioperative shoulder surgery setting. The authors sought to determine whether patients with epilepsy undergoing shoulder arthroplasty would be at increased risk for in-hospital adverse events, prolonged length of stay, and nonroutine disposition. Using the National Inpatient Sample (2002-2011), 422,371 adults undergoing shoulder arthroplasty were identified, 3714 (0.9%) of whom had epilepsy. Comparisons of perioperative outcomes were performed by multivariable logistic regression modeling. The authors found that patients with epilepsy were more likely to experience postoperative adverse events (odds ratio [OR], 1.68; 95% confidence interval [CI], 1.54-1.84), including mechanical ventilation (OR, 3.91; 95% CI, 2.81-5.44), gastrointestinal complication (OR, 3.86; 95% CI, 2.78-5.37), deep venous thrombosis (OR, 3.23; 95% CI, 2.22-4.69), pneumonia (OR, 1.66; 95% CI, 1.35-2.04), posthemorrhagic anemia (OR, 1.57; 95% CI, 1.42-1.73), transfusion (OR, 1.56; 95% CI, 1.41-1.72), and acute renal failure (OR, 1.34; 95% CI, 1.04-1.74). An epilepsy diagnosis was also associated with increased odds for prolonged hospital stay (OR, 1.39; 95% CI, 1.28-1.52) and nonroutine discharge (OR, 1.80; 95% CI, 1.67-1.94). This study concludes that patients with epilepsy are at higher risk for early postoperative complications and resource use following shoulder arthroplasty surgery. Awareness of these risks may allow more targeted perioperative management of these patients to optimize postoperative outcomes and limit complications. [Orthopedics. 2016; 39(6):e1075-e1079.].