OBJECTIVE: To study the function of Qiyeling Decoction in inducing apoptosis of transplanted human lung adenocarcinoma cells A549 in nude mice. METHODS: Nude mice with transplanted A549 tumor were randomly divided into the untreated control group (group A), chemotherapy treated group (group B), chemotherapy plus Qiyeling Decoction treated group (group C), Qiyeling Decoction treated group (group D) and managed correspondingly. The tumor volume was measured and calculated into tumor weight. The apoptosis of tumor cells were examined using in situ cell apoptosis detection kit. RESULTS: The tumor weight was lower obviously in groups B, C and D than that in group A (P<0.05). The apoptosis of tumor cells was lower obviously in groups B, and C than that in group D (P<0.05). Cells in group A appeared perfect differentiation during the early stage and apoptosis later. CONCLUSION: Qiyeling Decoction can induce A549 cell apoptosis in nude mice.