Triletide is a tripeptide derivative which shows cytoprotective and antiulcerogenic activity. It is a thromboxane synthase inhibitor. Analysis of both individual and pooled data indicated that triletide was well absorbed after oral administration, with a lag time of 0.3 hours and the blood peak was reached after about 1.1 to 1.3 hours. Metabolization to desmethyl, desacetyl, desmethyl-desacetyl and hydroxylated derivatives plays a major role in the biotransformation of the drug and thus in its disappearance from blood, the distribution half-life being about 1 hour. A greater proportion of patients given the combination cimetidine and triletide was found to be endoscopically healed after treatment in comparison with those who had cimetidine alone (53% vs 40%). Intensity of symptoms decreased significantly faster and to a significantly greater extent in the same patients, as did antacid intake. Triletide appears to be equally well tolerated as, but significantly more effective than, aluminium hydroxide and magnesium hydroxide in relieving symptoms and promoting healing in patients with mild to moderate duodenal ulcer. There were no complaints of possible side-effects with either triletide treatment and no evidence of any significant changes in blood pressure, heart rate or routine haematology and haematochemistry investigations.