Fifty-three consecutive patients with active duodenal ulcer (DU) were randomly included in a double-blind, double-dummy study to test the healing and relapsing rate of two treatment regimens: famotidine 40 mg nocte for 4-8 weeks, followed by 20 mg for 12 months after healing of the ulcer and colloidal bismuth (CBS) (240 mg bid) for 4-8 weeks, followed by placebo maintenance treatment. The results of the short term period confirmed the efficacy of CBS in healing DU (24/25 in CBS group and 19/23 in famotidine group). However, the relapse rate in the CBS-treated group was higher (77.8% at 12 months) than in the famotidine group (35.7%) (p = 0.041). Only 7 patients (41.2%) were cleared from Helicobacter pylori (HP) after CBS treatment. In conclusion, the high relapse rate observed in CBS treated patients may be related to the high percentage of patients with HP infection in the tested group and support the hypothesis that lack of efficacy of CBS in preventing DU recurrence is related to its poor eradication of HP.