['Although laparoscopy now plays a major role in most general surgical procedures, little is known about the relative risk of venous thromboembolism (VTE) after laparoscopic compared with open procedures.', 'To compare the incidence of VTE after laparoscopic and open surgery over a 5-year period.', 'Clinical data of patients who underwent open or laparoscopic appendectomy, cholecystectomy, antireflux surgery, and gastric bypass between 2002 and 2006 were obtained from the University HealthSystem Consortium Clinical Database. The principal outcome measure was the incidence of venous thrombosis or pulmonary embolism occurring during the initial hospitalization after laparoscopic and open surgery.', 'During the 60-month period, a total of 138,595 patients underwent 1 of the 4 selected procedures. Overall, the incidence of VTE was significantly higher in open cases (271 of 46,105, 0.59%) compared with laparoscopic cases (259 of 92,490, 0.28%, P < 0.01). Our finding persists even when the groups were stratified according to level of severity of illness. The odds ratio (OR) for VTE in open procedures compared with laparoscopic procedures was 1.8 [95% confidence interval (CI) 1.3-2.5]. On subset analysis of individual procedures, patients with minor/moderate severity of illness level who underwent open cholecystectomy, antireflux surgery, and gastric bypass had a greater risk for developing perioperative VTE than patients who underwent laparoscopic cholecystectomy (OR: 2.0; 95% CI: 1.2-3.3; P < 0.01), antireflux surgery (OR: 24.7; 95% CI: 2.6-580.9; P < 0.01), and gastric bypass (OR: 3.4; 95% CI: 1.8-6.5; P < 0.01).'] Is laparoscopic surgery associated with a lower incidence of venous thromboembolism compared with open surgery?