Among 4608 patients with gastric carcinoma treated during a 20-year period from 1971 to 1990, 328 (7.1%) were less than 40 years of age. The clinicopathologic features and treatment results in this young group were compared with those for older gastric carcinoma patients (40-79 years of age, control group). In the young group, the male/female ratio and the prevalence of tumors in the lower third of the stomach were both lower than in the control group, and undifferentiated-type adenocarcinomas with diffusely infiltrative growth predominated. The TNM stage distribution and the proportion of curative resections were similar in the two groups. The overall cumulative 5-year survival rates were also similar, although that of patients who underwent curative resection was higher in the young group, due probably to the low rate of death from other causes. There was no difference in the recurrence rates after curative resection between the two groups. Contrary to widely held belief, the prognosis of young patients with gastric carcinoma is not poorer than that of older patients if the disease is diagnosed at a reasonably early stage.