Pregnant golden Syrian hamsters were given single or multiple intragastric doses of Δ9‐tetrahydrocannabinol (Δ9‐THC) dissolved in olive oil. Dose levels of 125, 250, or 500 mg/kg were administered by gavage once during gestational days 7–12 and of 25, 50, or 100 mg/kg daily on days 7–10, 9–12, or 7–12 in the two experimental series. Untreated and vehicle‐injected controls were used for each series. All fetuses were examined on day 15 of gestation. Larger doses of Δ9‐THC induced a high frequency of fetal mortality and growth retardation. Vehicle‐injected controls showed up to 3% fetuses with external anomalies and several Δ9‐THC treated samples had higher frequencies, ranging up to 7%, but a majority of the samples did not show any statistical difference between the Δ9‐THC treated and corresponding control groups. However, a single dose of 500 mg/kg Δ9‐THC given on day 10 and four daily doses of 100 mg/kg Δ9‐THC on days 7–10 produced significantly higher frequencies (p < 0.05) of external anomalies, 5.36% and 4.17%, respectively, than their corresponding controls. Most of the defects were relatively minor in severity. In general, hamsters appeared to be relatively resistant to the teratogenic effects of pure Δ9‐THC, in contrast to the previously reported high teratogenicity by crude cannabis extract in this species. It is likely that the latter effect was not due to the action of Δ9‐THC but may have been the result either of interaction of various cannabinoids or of impurities in the crude preparations. In view of the data presented, it can be concluded that Δ9‐THC did not induce a clear‐cut teratogenic response in hamsters, although a slightly higher frequency of minor defects was observed in the fetuses from Δ9‐THC treated dams than in the controls.