Morphological transformation, cell survival, chromosomal aberrations and micronuclei were measured in C3H/101/2CL8 cells after 24 hour exposure to amsacrine. A weak but dose-related increase in the percentage of dishes containing transformed foci occurred. As previously reported for alkylating agents, this effect was increased by treating 5 days instead of 1 day after plating. There was no evidence for gene mutation at the Na/K ATPase locus, although amsacrine induced micronuclei in a large percentage of cells and chromosomal aberrations, including interchange events and double minute chromosomes, in dividing cells. It would appear that transformation and chromosomal events may be related in amsacrine treated C3H/10T1/2CL8 cells. The results strongly suggest that amsacrine has carcinogenic potential, possibly related to its chromosome-breaking properties. (Copyright (C) 1986 Elsevier Science Publishers B.V.)