The incidence of operations for peptic ulcer increased in Singapore during the period 1951 to 1980 (males from 12.1 to 40.0 per 100,000 per year; females from 1.1 to 13.2 per 100,000 per year). This increase is due to an increase in surgery for both perforated and non-perforated ulcers. While an increase in elective ulcer surgery may be due to a number of factors, the increase in surgery for perforated ulcers suggests that peptic ulcers have increased in frequency over this period. The incidence of peptic ulcer surgery amongst the Chinese was higher than that amongst the Malays and the Indians. For males, however, this difference between the Chinese and the Malays became less marked over the thirty years. In contrast, the difference between the Chinese and the Indians remained constant.