Thirteen malformed foetuses and one embryonic death were produced in 14 ewes fed Veratrum californicum on the 14th day of gestation. Ewes fed the plant on gestation days 11, 12, 13, 15 and 16 all had normally developed foetuses or normally developed embryos which had died between the 18th and 23rd days of embryonic development. All embryonic deaths occurred in ewes that had severe clinical signs of poisoning, but the only embryonic deaths accompanied by malformation occurred in ewes fed V. californicum on the 14th day. Four of the 14 ewes fed the plant on gestation day 14 did not have clinical signs of poisoning but produced malformed foetuses. The dosage of V. californicum that had a teratogenic effect was less than that necessary to cause clinical signs of poisoning in ewes. (AS).