Establishment of laboratory models of gynecologic neoplasms provides an important means of studying the biologic characteristics of these tumors. We report a previously uncharacterized human endometrial adenocarcinoma cell line that produces both intraperitoneal and subcutaneous growth in nude mice. The line was derived from a poorly differentiated endometrial cancer and has been carried in continuous tissue culture for greater than 100 passages. Doubling time in culture is approximately 48 hr. Antigenic phenotyping against a panel of murine monoclonal antibodies by rosetting cell surface assay on live cells or peroxidase assay on fixed cells has shown reactivity with a number of determinants, including MH99, MT334, MQ49, and the blood group antigens F3, 118, and 41-83. Cytogenetically, the line displays an aneuploid human karyotype with several chromosomal rearrangements and deletions. When injected intraperitoneally into nude mice, animals develop intraperitoneal nodules and ascites and succumb with wasting in 30-40 days. The intraperitoneal tumor has been passaged multiple times in nude mice by direct transfer of ascites. Subcutaneous injection of tumor cells produces nodules that grow at a reproducible rate. By light and electron microscopy, the nude mouse tumor is a poorly differentiated adenocarcinoma, similar to the original patient's tumor. It expresses both estrogen and progesterone receptors. CA 125 is not elevated in the serum of animals with tumor implants. The line appears to be cisplatin sensitive as determined by rates of growth of subcutaneous nodules. This cell line may be useful in studying the in vitro and in vivo properties of human endometrial carcinoma.