A cell line of a squamous cell carcinoma of human skin (HSC-I) has been established in vitro, and successfully maintained proliferative in continuous tissue culture for about 2 1/2 years since March 1978. Another cell line (HSC-Ib) has been established in vitro from the recurrence of the same cancer. It has been maintained for about 8 months since December 1979. 3T3 feeders were used in the initial cultures in both cases. The cells grow in a monolayer in vitro and are epithelioid with anaplastic features. Chromosome analysis of HSC-I, frozen and thawed HSC-I, the transplanted tumour in a nude mouse and HSC-Ib all showed hypotetraploidy with the modal number 80, which reconfirms that HSC-I derives from the original skin tumour. The cell line is available to other investigators.