Coniine, an alkaloid of Conium maculatum (poison hemlock), was administered by gavage to immature chickens, quails, and turkeys at 0, 25, 50, and 100 mg/kg body weight. At 25 mg coniine/kg body weight, clinical signs were observed only in quails (2/10) and consisted of excitement, depression, hypermetria, seizures, opisthotonos, and flaccid paralysis. Chickens (9/10) and quails (8/10) dosed at 50 mg/kg body weight were affected, and several birds of each species died (2/10 and 5/10, respectively). Turkeys (7/10) were affected only when dosed at 100 mg/kg body weight, and quails (6/10), turkeys (4/10), and chickens (10/10) died at this dose. There were no gross or microscopic lesions. Coniine was detected in skeletal muscle and liver of birds dying after ingestion and was present in some survivors 7 days post-treatment.