Background/Aims: A prospective, multicenter observation study was conducted to investigate the effectiveness of antibiotic prophylaxis in the operative treatment of appendicitis. Methods: Between June 1996 and May 1997, a total of 4,968 patients underwent an operation for appendicitis at 34 East German hospitals. 41.4% (n = 2,424) received perioperative antibiotic prophylaxis whereas in 58.9% of the cases this was not given. The patients who received antibiotic prophylaxis constituted a negative selection, both with regard to risk factors and to the stage of inflammation. Results: In the total test group, the rate for septic disorders of wound healing amounted to 2.5% (n = 120). The use of antibiotic prophylaxis makes it possible to significant lower the incidence of postoperative septic disorders of wound healing (p < 0.001). In both conventional (0.7% with prophylaxis vs. 3.8% without) and in laparoscopic appendectomy (0 vs. 1.0%) the rate for septic disorders of wound healing can be reduced (p < 0.001). The global comparison irrespective of possible antibiotic prophylaxis shows a significant advantage for appendectomies which started with laparoscopy (p = 0.008), but in the subgroups with prophylaxis this advantage is completely neutralized (p = 0.78). Conclusion: From this one can deduce that conventional appendectomy with antibiotic prophylaxis comprises no higher risk of wound infection than laparoscopy, since the risk of conversion exists for every operation begun by laparoscopy. These results would lead to the conclusion that antibiotic prophylaxis should be given before every appendectomy, whether by laparoscopy or conventional methods.