Pregnant DBA/2J, C3H/HeJ, and ICR/Ha mice were injected intraperitoneally with vincristine sulfate on day 9 of gestation. The mothers were killed on day 17 and the fetuses were examined for various defects. A high incidence of fetal mortality, congenital anomalies, and growth retardation was induced in all three types of mice. DBA's were most susceptible to the teratogenic effects of the drug. Anomalies involved the central nervous system, eyes, limbs, tail and ribs, and most fetuses had more than one anomaly. Most of the types of anomalies observed were similar to those reported in rats, but dose required to produce malformations was much higher than that reported for rats, hamsters and monkeys. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company