Among 888 patients who underwent operation or endoscopic resection for gastric cancer (1994-1998), 75 patients, who had no colorectal disease or only small polyps 5 mm or less in diameter, were positive on the immunologic fecal occult blood test (IFOBT) (the positive group). They are compared with the other 813 patients (the negative group) as to the following 6 points: symptoms, presence of anemia, depth of invasion including macroscopic appearance, location, maximum diameter of lesions, and microscopic findings. The rate of positive-IFOBT gastric cancer was 8.4%. The average blood hemoglobin concentration was significantly lower in the positive group than in the negative group. Advanced cancers, especially type 2 and 3, were significantly more frequent in the positive group than in the negative group. The size of the lesions tended to be larger in the positive group than in the negative group. There was no difference between the groups as to symptoms, location, depth of invasion and microscopic findings. In conclusion, IFOBT-positive patients who have no colorectal disease or only small polyps 5 mm or less in diameter should be recommended to undergo upper gastrointestinal endoscopy.