A cell line designated SKG-1 was established in vitro from human uterine-cervical epidermoid cancer which contained minor components of clear cell epidermoid cancer. Cultured cells have grown without interruption for over 6 yr. The monolayer cultured cells appeared in epithelial in shape, showing pavement arrangement and piling up tendencies without contact inhibition. Cytology revealed anaplastic and pleomorphic features. In EM 2 types of cells were observed, one with many tonofilaments and desmosomes and the other with much glycogen in cytoplasm. Chromosome studies showed aneuploidy and modal numbers of 74 and 75. There was no apparent marker chromosome. The doubling time was 35-42 h and plating efficiency was 70-88%. Heat-stable, L-phenylalanine-sensitive alkaline phosphatase (Reagen-like isoenzyme) was observed in the cultured cells. The SGK-1 cells were transplanted subcutaneously to nude mice and submucosally to immunodepressed hamster cheek pouches and produced tumors resembling the original tumor.