- Objectives To look for an association between the measles virus and endometrial carcinoma, the most frequent cancer of the female genital tract in our area. Study design Thirty-six of 49 patients with endometrial carcinoma were studied to detect fingerprints of the measles virus. Immunohistochemistry with the avidin–biotin complex method and in situ hybridization were used to demonstrate the association. The clinicopathological correlations were carried out to support a relationship between the virus and the cancer if any was found. Results Twenty-six of the 36 cases (72%) of endometrial cancer showed the presence of measles virus antigens in the tumor cells. Sixteen of 21 cases were positive for measles virus RNA by in situ hybridization. Although type I endometrial carcinoma was more positive for viral particles than type II, type II cancer, when allied with the measles virus, was more often associated with the depth of myometrial invasion and with death from tumor. Conclusions We demonstrate for the first time a link between endometrial cancer and the presence of viral antigens and RNA of the measles virus, although these findings do not necessarily signify a causal relationship between the cancer and the virus.