Objective. Our goal was to characterize variation in complication rates across hospitals with differing volumes for select high-risk operations in the United States. Methods. Data from the Nationwide Inpatient Sample for 1996 and 1997 were analyzed for 3 high-risk operations: esophagectomy (n = 1,226), pancreatectomy (n = 4,789), and intact abdominal aortic aneurysm repair (n = 11,863). Complications evaluated included aspiration, cardiac complications, infection, pneumonia, pulmonary failure, renal failure, septicemia, and others. The risk of complications was calculated by hospital volume deciles, as well as for high-volume hospitals (HVH) and low-volume hospitals (LVH) defined by median hospital volume. Results. Rates of any postoperative complication varied nearly 2-fold across hospital volume groups. The proportion of patients across hospital deciles having at least one complication ranged from 30% to 51% for esophageal resection, 6% to 12% for pancreatic resection, and 9% to 18% for abdominal aortic aneurysm repair. HVH had lower rates of one or more complications after pancreatic resection (OR, 0.71; 95% CI, 0.57 to 0.83; P = .002), esophageal resection (OR, 0.68; 95% CI, 0.52 to 0.90; P = .008), and intact abdominal aortic aneurysm (AAA) repair (OR, 0.67; 95% CI, 0.59 to 0.76; P < .001). Patients with one or more complications after pancreatic resection had a mortality of 18.8% versus only 5.2% for those without complications (P < .001). Esophageal resection mortality was 16.9% for patients with at least one complication and 2.5% for those without complications (P < .001) and AAA repair mortality was 10.4% for patients with at least one complication and 2.9% for those without complications (P < .001). Conclusions. High-risk operations have a decreased rate of postoperative complications when performed at HVH. Variation in complication rates may contribute to the volume-outcome relationship and provide a focus for quality improvement at LVH.