Clinical and pathological findings of gastric cancer in patients of less than 30 years of age were compared with those in aged patients of over 75 years of age. These were 10 males and 24 females, and the rate of gastric cancer for females in the younger group was extremely high. There were marked differences between both groups in the pathological findings of gastric cancer, and consequently in the progressive pattern of the disease, perhaps as the result of differences in the matrix of cancer development and the influence of sex hormones. Gastric cancer at an advanced stage and delayed surgery in younger patients are attributable to negligence on the part of the patient in scheduling a medical examination and careless diagnosis by the physician. However, the prognosis of gastric cancer was not unfavorable in the younger patients when curative surgery was performed.