Prior to employing the Fischer 344 rat in teratology studies, it was considered necessary to establish the responsiveness of this strain to teratogenic agents. Bred Fischer 344 rats were administered 0, 3.2, 32, or 128 mg/kg/day (approximately 1,000, 10,000, or 40,000 USP units per animal) of vitamin A palmitate by gavage on days 6 through 15 of gestation. Maternal toxicity, as evidenced by decreased body weight gain, and decreased food and water consumption, was observed at the 128 mg/kg/day dose level. This dosage level was embryolethal and teratogenic in the Fischer 344 rat. The incidence of fetal resorptions was statistically significantly increased as compared to controls. Among the surviving fetuses, malformations observed included cleft palate, exencephaly, microphthalmia, anophthalmia, hydronephrosis, brachygnathia, pinna anomalies, and great vessel and heart anomalies. Based on these findings, it is concluded that the Fischer 344 rat responded to a known teratogenic agent and hence is appropriate for use in studies designed to evaluate the teratogenic potential of test agents.