The first reference concerning the multiple primary malignant neoplasms was made by Bilroth, 1880 and since then a large number of studies have been published. Furthermore, an increasing incidence of simultaneous cancers are currently observed (16,18). At the same time, several retrospective populational studies evidenced the association between breast and endometrium carcinoma. It is well known that both uterus and breast are hormone-dependent organs and are likely to be influenced by the same oncogenic stimulus, either of endocrine nature or dietary origin (2, 3, 14). The risk of developing endometrial carcinoma is higher in patients already affected by breast neoplasm and is much more evident in older women within the first five years following the diagnosis of breast tumor. Conversely, patients with endometrial carcinoma may present a second mammary neoplasm and the relative risk is around 2.0 (1, 17). Although the existence of a correlation between these two primary malignant neoplasms is clearly observed, the absence of systematic studies directed to the screening of endometrial cancer in women with breast carcinoma is surprising. This study deals with histological analysis of the endometrium of postmenopausal patients with breast cancer and aims to determine the possible changes that might have occurred in the onset of the disease.