A new cell line (XTY) was derived from a tumor of a female Xenopus laevis. This cell line has been proliferating in standard amphibian culture medium for more than 4 years (470 generations) and has a doubling time of 75.5 h at 25 degrees C. The cells aggregate into large groups, and their stellate morphology and the expression of desmin demonstrated by immunocytochemistry suggest that their origin is not epithelial.