Gastric cancer is a highly fatal, common form of cancer in many countries and its medical, surgical, radiologic or combined treatment is very problematic. Thus, a search for its cause and prevention may be more promising than a search for its cure. Epidemiologic data from international studies suggest that environmental factors are more influential than genetic ones in the pathogenesis of gastric cancer, although its causes have not yet been identified. It is likely that the disease has a multi-factorial pathogenesis and that an ingested carcinogen may exert its influence at a time of enhanced susceptibility (damaged mucosa, older age, etc.), particulary in individuals with inherent, elevated risk (males, selected hereditary background etc.). In general, dietary studies have been less rewarding than occupational and geographic-pathologic analyses; such investigations may eventually identify the crude sources of carcinogens which then can be isolated by chemical means.