We describe a case of persistent postoperative bleeding following total hip arthroplasty in which, initially, no obvious cause was identified. The patient was taking ginkgo biloba extract, an unlicensed herbal medicine taken to improve mental alertness. Ginkgo biloba is an anticoagulant that inhibits platelet-activating factor and is contraindicated with aspirin. Four weeks' postoperatively, the ginkgo was stopped, and the bleeding stopped 6 weeks later.