The various hypothesis for the explantation of reversible bismuth encephalopathy are reviewed and discussed. Today, this side effect appears to be devoid of mystery, due to uncontrolled and inhibited ingestion of bismuth salts which increased the emergence of genetic and physiopathologic risk factors and brought about the cases of neurotoxicity. Bismuth therapy has shown major efficacy in the treatment of gastroduodenal ulcers. Colloidal bismuth subcitrate is as effective as the H2-receptor antagonists in peptic ulcer. In addition, it offers a lower rate of relapse. This therapeutic benefit has been attributed to a cytoprotective and demulcent action. Moreover bismuth acts as an antimicrobial agent, suppressing the organism Helicobacter pylori which occupies a central place in contemporary views on pathophysiology of ulcer disease. Side effects so far reported have been very infrequent mild and transient when the drug is used at low dosage providing blood-bismuth concentration above toxic values. Colloidal bismuth subcitrate complies to the requirements for a modern drug insofar as it is prescribed in period no longer than 6-8 weeks, followed by 8 weeks bismuth-free intervals.