Castor beans (Ricinus communis) contain ricin. Ricin is a glycoprotein reported to cause hypotension, gastroenteritis, depression, and death. However, few deaths are reported following castor bean ingestion in animals. From January 1987 to December 1998, the American Society for the Prevention of Cruelty to Animals-National Animal Poison Control Center received 98 incidents of castor bean ingestion in dogs. The most commonly reported clinical signs were vomiting, depression, and diarrhea. Death or euthanasia occurred in 9% of the cases. The severity of clinical signs following castor bean ingestion may depend on whether the beans were chewed or swallowed whole.