A new human endometrial cell line, SCRC-1, has been established from a uterine adenocarcinoma. During a period of 57 weeks in culture, the SCRC-1 cells have been passaged over 100 times. Cultures have an epitheloid morphology, high mitotic activity, and a tendency to form multiple cell layers. The cells are polygonal and are arranged in pavement-like fashion. Most have multiple nucleoli, some are multinucleated, and all have heavily vacuolated cytoplasm. Pretreatment with iododeoxyuridine did not reveal viral markers by cocultivation or immunofluorescence techniques. Karyologic studies indicate that the SCRC11 cell line is essentially diploid with a small subpopulation of tetraploid cells. Over a period of 20 weeks, 1 of 14 athymic nude mice inoculated with SCRC-1 cells developed a tumor which histologically closely resembled the original human tumor. Cells were subsequently propagated from this tumor and the resulting epitheloid-like cell line was designated SCRC-1, Tu 1.