Based upon literature data, a 2-fold risk for gastric and colorectal cancer and a 2- to 5-fold risk for pancreatic cancer are predicted after remote peptic ulcer surgery. The association between previous ulcer surgery and subsequent gastric cancer appears firm; the linkage between colorectal and pancreatic cancer is more tenuous. Increased formation of carcinogens in the hypochlorhydric stomach following gastric surgery may be incriminated. Other conditions have features in common with the operated stomach and are also thought to be a suitable microenvironment for the subsequent development of cancers. Viewed in that light, further research of the putative relationship between peptic ulcer surgery and carcinogenesis and their underlying mechanism is highly desirable. Molecular cancer epidemiology and environmental pathology are proposed as useful tools for such studies. In the long run, the hypochlorhydric stomach might be a condition suitable for the chemoprevention of cancer.