One hundred patients were entered into a double-blind, double-dummy comparison of tripotassium dicitrate bismuthate (TDB) versus ranitidine, to evaluate short-term healing rates, and successfully healed patients were then entered into a follow-up phase to observe relapse rates. At 4 weeks 84% of patients treated with TDB and 68% of those treated with ranitidine had healed. At 8 weeks these figures had risen to 96% and 90%, respectively (p = NS). After a year's follow-up study 84% of patients healed initially with ranitidine had relapsed, whereas in the case of patients healed initially with TDB the relapse rate was 67% (p less than 0.05). The results confirm that in the short term, TDB is as effective as ranitidine, whereas the significantly better protection against relapse offered by TDB compared with ranitidine underlines the importance of restoring mucosal defence, an approach that to date has been somewhat overlooked.