The demographic characteristics (sex, age, occupation) of patients with cancers of the esophagus, stomach and colon are reported and the importance of smoking and consumption of alcohol and coffee in development of the disease have been evaluated. The etiologic studies comprised 366 patients (100 with esophageal cancer, 80 with stomach cancer and 186 with colon cancer) and 366 controls. NcNamary test was used in differentiation of the rates of the matched samples. The most significant relationship of smoking and alcohol consumption was found for esophageal cancer (RR = 4.4; RR = 9.0, p 0.0001), somewhat less for stomach cancer (RR = 2.0, p 0.05; RR = 1.5) and least for colon cancer (RR = 0.9, RR = 1.1). Coffee consumption was most frequent in patients with cancer of the esophagus and colon while negative correlation was obtained for stomach cancer.