We analyzed a novel cell line established from a testicular feminization syndrome. The original tumor was an endodermal sinus tumor with seminoma. The doubling time, the saturation density and the mitotic index were 36.1 hours, 3.65x10(4) cells/cm2 and 4.3%, respectively. The mode number of chromosomes was 102. Results of the MTT assay showed that the cell line had an IC50/PPC of less than 0.1 for methotrexate and actinomycin D. The effects of methotrexate were schedule dependent; the effects of actinomycin D were both schedule and dose dependent.