The patient was aged 71 yrs., female. Tumors respectively of the oral mucosa, lung and stomach in this case were discovered almost simultaneously. The triple tumors were all histologically malignant, while differing from each other in their morphological characteristics. According to statistics based on"Annual of the Pathological Autopsy Cases in Japan", cases of multiple primary malignant tumors in 4 years (1970-1973) amounted to 1, 207 (1.34% of the whole autopsy ases). Of these multiple malignant tumors, double malignant tumors were seen in 1, 157 cases (1.29%), and triple malignant tumors in 49 cases (including our case) (0.05%). Distribution of the sites of the triple malignant tumors shows that the digestive organ was the site of all the 3 tumors in 8.16%, that of 2 tumors in 38.78%, and that of only I tumor in 36.73%. The organs in which triple tumors evelop are also the sites of frequent development of a single tumor.