To determine the effect of modern drug treatment on the incidence and type of ulcer operations, a retrospective survey was made of ulcer surgery performed on adult Helsinki residents during the years 1972, 1977, 1982 and 1987, with regard to indications and types of surgery. The introduction of H2-receptor blockers in 1979 was followed by a marked reduction in the incidence of elective ulcer surgery. On a population basis, the annual incidence of duodenal ulcer (DU) operations diminished by 50 per cent over the period 1972-1987, and that of operations for gastric ulcer by about two thirds, the falling trend being most marked among male DU patients. Figures for emergency surgical intervention in cases of haemorrhage or perforation remained unchanged during the period, as did the mean age of patients admitted for elective surgery, though the mean age of patients undergoing emergency surgery manifested a rising trend. The number of patients undergoing elective surgery for DU diminished, a trend first and foremost attributable to the fact that proximal selective vagotomy was performed more rarely, while the number of resections increased. The incidence of surgical treatment of pyloric and gastric ulcers remained unchanged during the period.