Continuous ambulatory peritoneal dialysis (CAPD), a widely used replacement therapy for end stage renal failure, is frequently complicated by bacterial peritonitis. The infecting organisms are mainly staphylococci and gram negative aerobes. Pefloxacin is a fluorinated quinolone with good in-vitro activity against these pathogens. The objective of this open non comparative study is to determine the effectiveness and safety of oral pefloxacin mesylate as a single first line antimicrobial treatment of CAPD peritonitis. 28 episodes of CAPD peritonitis were treated with a stat dose of pefloxacin 800 mg. followed by 400 mg. 12 hourly for about 15-18 days. A pefloxacin sensitive organism was isolated in 17 episodes. 11 episodes were culture negative. Treatment results showed a cure in seventeen (60.7%), no treatment response in seven (25%), and relapses in four (14.2%). Side effects encountered were not serious except for one incident of a generalized seizure. We conclude that oral pefloxacin is convenient, safe and effective enough as a single first line antimicrobial treatment for CAPD peritonitis.