U.S. Food and Drug Administration (FDA) approval of new drugs expands treatment options and serves as a "safety net" of well-documented efficacy and safety. The information provided in the package insert facilitates physician education and provides some assurance that marketing information is accurate. As of February 1997, three Helicobacter pylori regimes have been FDA-approved for eradication of H. pylori in infected patients with active duodenal ulcers. Regimen 1, omeprazole + clarithromycin (O/C), was supported by two multicenter, controlled studies with a 6-month follow-up. Eradication rates were 74% (n = 53; 95% confidence interval [CI], 62-85) and 64% (n = 61; 95% CI, 52-76). Twenty-five of 26 patients with failed eradication therapy who were taking O/C with clarithromycin-susceptible strains before treatment and who had pretreatment and posttreatment susceptibility tests performed developed clarithromycin resistance after treatment. Regimen 2, ranitidine-bismuth-citrate + clarithromycin, was supported by two multicenter, placebo-controlled studies with a 6-month follow-up. Eradication rates were 84% (n = 19; 95% CI, 60-96) and 73% (n = 22; 95% CI, 50-88). Insufficient pretreatment and posttreatment susceptibility data were collected to assess antimicrobial resistance. Regimen 3, bismuth subsalicylate + metronidazole + tetracycline + an H2-receptor antagonist, was supported by two pivotal literature-based studies. Eradication rates in patients with duodenal ulcer were 82% (n = 51; 95% CI, 70-92) and 77% (n = 39; 95% CI, 61-89), respectively. When extrapolating the results of these three FDA-approved regimens to the clinical setting, particular aspects of the clinical trial should be kept in mind. These include the type of controls, primary end points used, population studied, and number and type of dropouts.