A female infant weighing 3860 g was born at 40 weeks’ gestation to a healthy 24-year old woman. The obstetrician reportedly had advised the woman to drink a tea made from Caulophyllum thalictroides (blue cohosh). Induction of labour is a recognised effect of this herbal supplement and the tea was effective. A Caesarean section was performed after a failed vaginal delivery. The infant developed focal motor seizures of the right arm, which began at 26 h of age and were controlled with phenobarbital and phenytoin. A computed tomographic scan showed an evolving infarct in the distribution of the left middle cerebral artery. The results of thrombophilia studies on the infant were either negative or normal and the family history was negative. Urine and meconium were positive for the cocaine metabolite benzoylecgonine. Testing of the contents of the mother’s bottle of C. thalictroides and the contents of a sealed bottle of a different preparation of the herb gave the same results. These studies suggest that either benzoylecgonine is a metabolite of both cocaine and C. thalictroides or the C. thalictroides was contaminated with cocaine.