Abstract: Lycorine hydrochloride (m.p. 205—207℃) was prepared by the Kunming Pharmaceutical Factory of Yunnan Province, which is an alkaloid of Lycoris aurea Herb. produced in Yunnan Province of China.In the present work, the authors have investigated the action on the uterus with a 0.1% lycorine hydrochloride solution. The following are the results. 1. The stimulative actions of the drug are evident on rabbit's and guinea pig's uterus, uterus in situ and uterus-fistula of rabbits. 2. On isolated rat's uterus, the drug causes stimulation with minimal doses, but inhibitory action with large doses. 3. The LD₅₀ of lycorine hydrochloride for mice given hypodermically was found to be 42 mg/kg.The chief symptoms before death were salivation, convulsion, and dyspnea.