['Although norfloxacin (N) is widely accepted as the drug of choice for spontaneous bacterial peritonitis (SBP) prophylaxis, there is data to suggest that trimethoprim-sulfamethoxazole (TS) may be similarly effective. However, no studies have compared the efficacy and safety of N and TS in SBP prophylaxis. The aim of this retrospective analysis was to compare outcomes in patients who received either N or TS for the prevention of SBP.', 'Records of all cirrhotic patients prescribed either N or TS for SBP prevention between April 2001 and May 2004 were reviewed. Data collected included age, sex, Child-Pugh score, ascitic protein concentration, etiology of liver disease, infections (SBP, bacteremia, and extraperitoneal infections), side-effects, and survival.', 'Sixty-nine patients (18 female, 51 male), mean age 53.9 +/- 10.6 years, were prescribed N (n = 37) or TS (n = 32). The Child-Pugh score, model for end-stage liver disease score, and the prevalence of a low ascitic protein (<15 g/L) were similar between the groups (12.0 vs 12.4, 19.7 vs 18.2, and 78% vs 84%, respectively, P > 0.05). Fourteen (38%) infections occurred in the N group and 16 (50%) in the TS group (P > 0.05). Eight patients (21.6%) in the N group and nine (28%) in the TS group developed SBP (P > 0.05). The rates of liver transplantation (10 vs 13), adverse events (two in each group) and death (13 vs 14) were similar in the two treatment groups.'] Do norfloxacin and trimethoprim-sulfamethoxazole therapy have similar efficacy in prevention of spontaneous bacterial peritonitis?