In phase II clinical trial of Compound Prescription of Huangyaozi (Dioscorea bulbifera L.), 7 cases out of 37 developed (18.92%) impairment of liver function. As a result, the ethic committee required researchers to report all data of safety of the drug and have all subjects rechecked about their liver function so as to provided reasonable evidence for the scientifical evaluation of the relationship between the drug and the adverse event and the succedent suspending of the clinical trial.