Laparoscopic-assisted colectomy is an emerging technology for patients with cancer, polyps, inflammation, and other types of pathologic conditions. While previous studies have shown better outcomes for laparoscopic cholecystectomies when surgeons perform more procedures, there is no information on the relationship between surgeon volume and outcomes for laparoscopic-assisted colectomy. To evaluate whether better clinical outcomes are found for surgeons who perform higher numbers of laparoscopic-assisted colectomies and whether such a relationship, if it exists, applies to both intraoperative and postoperative outcomes. Analysis of a data set of 1194 patients, operated on by 114 surgeons, from a prospective registry sponsored by the American Society of Colon and Rectal Surgeons, from May 1991 to October 1994. Completion rate, intraoperative and postoperative complications, and length of hospital stay. In 75% of cases, surgery was completed laparoscopically, with no difference between high-volume surgeons (> or = 40 cases) and low-volume surgeons. Length of stay (average, 6 days) did not vary according to surgeon volume. Postoperative complications occurred in 15% of cases, with a significantly lower rate for high-volume surgeons (10% vs 19%; P < .001). Intraoperative complications occurred in 5% of cases, with a nonsignificant trend toward a lower rate for high-volume surgeons (3.7% vs 6.3%). A multivariate regression analysis, adjusting for type of disease (cancer vs inflammation vs polyps) and for level of difficulty of the procedure (high vs low) showed that for high-volume surgeons there is a lower probability of both intraoperative complications (adjusted odds ratio, 0.56; 95% confidence interval, 0.32-0.97; P = .04) and postoperative complications (adjusted odds ratio, 0.48; 95% confidence interval, 0.34-0.68; P < .001). There is a learning curve for laparoscopic-assisted colectomy with respect to intraoperative and postoperative outcomes. As with other laparoscopic procedures, surgeons who perform higher volumes of laparoscopic-assisted colectomy have lower rates of intraoperative and postoperative complications.