Cell line CEC-32 and clone LSCC-H32 were established from primary chicken embryo cells spontaneously but not experimentally transformed at 32 degrees C. The lines consisted of fibroblastoid and polygonal cells and had a subtetraploid karyotype of 2N = 130 to 140. The cells showed increased plating efficiency and metabolic activities as demonstrated by hexose uptake and plasminogen activator assay. The established cells produced avian lymphoid leukosis viruses of subgroups A and B. The virus released from LSCC-H32 cells induced lymphoid leukosis in inoculated chickens 18 to 22 wk post infection (PI). The cells have been carried in continuous culture for 285 passages and they appeared to grow indefinitely. They were efficiently used to propagate several animal viruses and to titrate chicken interferon.