Duodenal ulcer relapse rates after therapy with sucralfate or bismuth are lower than those after H2-receptor antagonist therapy. This may be mediated by an antibacterial effect of these drugs on Helicobacter pylori. Bismuth has become an integral part of 'triple therapy' because of its documented anti-H. pylori effect. In vitro and clinical data suggest that sucralfate may also have an anti-H. pylori effect. The aim of this randomized, prospective therapeutic trial was to compare the efficacy of triple therapy containing bismuth with that containing sucralfate and to determine the effect of therapy with these combinations on duodenal ulcer relapse. Forty H. pylori-positive duodenal ulcer patients were healed with omeprazole and randomized to receive either 1 g sucralfate four times daily or 120 mg bismuth compound four times daily. All patients received 400 mg metronidazole three times daily and either 250 or 500 mg tetracycline four times daily for 7-14 days. Thirty-five patients could be analysed. Overall eradication rates did not differ in the treatment groups (10 of 17 eradicated with sucralfate and 11 of 18 with bismuth). Relapse rates were significantly lower in the eradicated group (1 of 21 compared with 8 of 14 in the non-eradicated group) and did not differ between treatment groups in those patients not eradicated. A triple therapy regimen utilizing sucralfate appears to be as effective as the bismuth-containing regimen.