We studied a cell line established from a primary non-small-cell lung cancer (non-SCLC) of human origin and characterized by midly differentiated epidermoid carcinoma, a human karyotype and keratin expression. Doubling time was about 48 h in vitro and 12 days when transplanted into nude mice. In vitro, this cell line was mainly sensitive to dactinomycin and mitotic poisons such as Vinca alkaloids. Most chemotherapeutic drugs proved ineffective. Our findings are comparable to previous results in patients who showed 30% objective response and less than 5% complete response regardless of the therapeutic associations used against non-SCLC. Our line would also seem to provide a good model for studying new potentially antitumor substances.