This report is based on 1,139 patients with gastric cancer (GC) detected by mass screening conducted by the Center for Adult Diseases, Osaka during 1961-1985. Early GC totalled 527 patients and advanced GC totalled 612 patients. In 859 patients curative resection was performed. Their vital status was traced yearly and six patients were lost to follow-up. Relative survival rates of screening-detected GC patients were 69-70% and almost constant after 5 years from operation/diagnosis. The survival curve in which only death from GC was counted as a death was almost equal to the relative survival curve in its shape and value. The hazard rates of screening detected GC patients decreased rapidly within 7 years and remained low after 7 years. It was confirmed by this long-term follow-up study that about two thirds of GC patients detected by screening were successfully cured of their disease.