A 33-year-old woman developed subacute hepatic necrosis after several months of ingestion of Chaparral Leaf, an herbal product. Symptoms first appeared 3 months after she began taking the tablets. The patient unwittingly carried out a clinical challenge by reducing, then increasing, the dose of pills. The public and the medical profession must be wary of all "harmless" nonprescription medications, whether purchased in pharmacies or elsewhere.