A cell line, designated KURATOU, was established from a human chorionic gonadotropin (hCG)-secreting pure dysgerminoma of the ovary. The cell line comprised small cells resembling original tumor cells and large ones possessing one or a few nuclei. Population doubling time was calculated to be about 10 days. An enzyme immunoassay study of hCG in media showed that the cells produced 7-9 x 10(-6) IU/cell of hCG. Immunocytochemical studies revealed hCG in almost all of the cultured cells. The chromosomal number was distributed in triploid and the modal chromosomal number was 69. Some cells contained HLA-ABC antigens, but none contained HLA-DR antigens. The cell line was transplanted into a nude mouse and produced a tumor resembling the original tumor but with no other tumor elements.