A permanent cell line has been established from an aflatoxin-induced hepatoma of rainbow trout. The cell line is now 17 years old and has been carried through 133 serial passages. Chromosome analysis indicates the cells are heteroploid and show a bimodal distribution with modal numbers of 54 and 60. Cells are routinely cultured at 18°C and are easily stored in liquid nitrogen.They are susceptible to both the viruses of infectious hematopoietic necrosis and infectious pancreatic necrosis. It is not known if these cells have undergone malignant transformation. However, numerous attempts to cultivate normal liver cells have failed. This culture may represent the first salmonid cell line derived from tumorous tissue.