There is a growing body of evidence that laparoscopic surgery is physiologically less injurious than open surgery. We hypothesized that the open technique results in a greater impairment of peritoneal and systemic defense mechanisms than does the laparoscopic technique. Nissen fundoplication, standardized in technique and duration, was performed in 16 pigs. The procedure was performed through a standard midline incision (OPEN, n = 8) or with laparoscopic technique and CO2 pneumoperitoneum (LAP, n = 8). The peritoneal cavity was instilled with 400 cc of normal saline, either alone (not contamined, n = 8) or containing 10(9) E. coli/ml (contaminated, n = 8). Quantitative cultures, cell count, and flow cytometry were performed on blood and peritoneal fluid samples obtained at timed intervals. We found that host defense processes were better preserved after LAP than by OPEN surgery. Peritoneal and systemic monocyte class II antigen expression, and serum tumor necrosis factor-alpha activity was greater in the OPEN group compared with the LAP group, but peritoneal bacterial clearance was more efficient in the LAP group. These data may illustrate a potential benefit of laparoscopic surgery in cases of peritoneal contamination.