Objective To evaluate the safety of Rongbisu capsule used for treating benign prostatic hyperplasia. Methods A total of 218 patients (average age 63.73±7.50 years old) with phase Ⅰor Ⅱ benign prostatic hyperplasia were treated with oral Rongbisu capsule at a dose of 3 granules twice daily. The therapeutic course was 6 weeks and hepatic function was determined every 2 weeks. Results The median value of ALT in 218 patients rose significantly after the patients took Rongbishu capsule for 6 weeks (P=0.001 7). There were 17 patients whose ALT level rose from normal to abnormal, the incidence was 7.80%. There were 3 patients whose hepatic function was seriously impaired (ALT＞200 IU/L). Conclusions The essential component of Rongbishu capsule is edible tulip which has been recorded in the medical literature as being toxic. Airpotato yam of which the alias is also edible tulip is easily mistaken for edible tulip. Airpotato yam is the tuber of dioscorea bulbifera L. (family dioscoreaceae) which has confirmed hepatotoxcity. Our study result indicates that in order to insure the safety of Chinese crude drug, the origin of Chinese crude drug should be defined in the formulation according to the standard of Chinese drugs preparation. Pharmaceutical enterprises should strictly abide by the standards to identify the origin of Chinese crude drugs when approving the raw materials, especially for species which are poisonous and easily mistaken.