Gastrointestinal tuberculosis has steadily decreased with the development of anti-tuberculous treatment, improvement of personal hygiene resulting from a rise in the standard of living, early diagnosis of pulmonary tuberculosis, and so forth. However, gastrointestinal tuberculosis can occasionally be found clinically in South Korea where the prevalence of tuberculosis is as much as 2.2%. Prevalence of gastric tuberculosis is low, compared with other gastrointestinal tuberculosis. While there have recently been several reports on the occurrence of gastric tuberculosis and duodenal tuberculosis assuming the form of malignancy, few cases have been reported of the tuberculosis affecting stomach and duodenum simultaneously. In this article we report the case in which tuberculosis affects both stomach and duodenum, which was initially misconceived as a double primary cancer. (Korean J Gastrointest Endosc 2004;29:142146)