In spite of several recommendations, choosing the initial antibiotic to treat continuous ambulatory peritoneal dialysis (CAPD) peritonitis remains difficult. In our prospective randomized study we attempted to evaluate the efficacy and safety of less toxic combinations of cephalosporins with vancomycin or netilmycin. From November 1993 to September 1996 we treated 52 episodes of peritonitis in 34 patients. Peritonitis was diagnosed according to the valid criteria. Patients were treated for 14 - 28 days with a combination of either cefazolin plus netilmycin or vancomycin plus ceftazidime. The most frequent bacteria causing peritonitis in the two groups were comparable. The efficacy of the cefazolin/netilmycin combination was 91.6% (22/24) without yeasts and 84.0% (21/25) in the vancomycin/ceftazidime combination. There were no statistically significant differences between the two otherwise efficient combinations of antibiotics. No side effects were observed. We believe that the frequent use of vancomycin could be avoided thus reducing the risks of resistance and ototoxicity.