AIM: To study the antitumor effect of Chinese compound Jinlongshe (JLS) granules on sarcoma 180 and MKN-45 human gastric cancer cell lines in vivo and its mechanism.METHODS: After establishment of S180 sarcoma (S180)and MKN-45 gastric cancer model of nude mice, the tumor-bearing mice were divided into 5 groups at random. Three experimental groups were respectively given the aqueous extract of JLS granules at doses of 120 g,60 g and 20 g/(kg per 6/wk, I.g) for 3 wk in S180 and 6 wk in nude mice model. Positive control was given cyclophosphamide (Cy)at a dose of 50 mg/(kg per 3/wk,I.g) for 3 wk in S180 models and 5- Fluorouracil (5-FU)20 mg/(kg per 3/wk, I.g) for 3 wk in nude mice model.Negative control was given normal saline (NS) at a dose of 0.18 g/(kg per 6/wk, I.g) respectively. After 3 wk in mice bearing S180 tumor and 6 wk in nude mice model,the experimental animals were sacrificed and the masses of tumor were weighed, and the rates of tumor inhibition of each treated group were calculated respectively. To determine the antitumor mechanisms, the morphologicai changes, cell cycle and apoptosis were observed in MKN-45 nude mice model. Annexin V-FITC/PI double staining FCM assay was used to further determine the live cells, apoptotic cells, necrotic cells and debris.RESULTS: The inhibitory rates of JLS granules at the doses of 20 g/kg, 60 g/kg and 120 g/kg were 50.31％,55.94％ and 68.13％ (P ＜ 0.01) in nude mice models and 40.90％, 50.32％ and 58.46％ (P ＜ 0.01) in S180 model. The inhibitory rate of Cy was 85.22％ in S180 models and the inhibitory rate of 5-FU was 53.43％ in nude mice model (P ＜ 0.01). Nuclear chromatin and margination were observed under a transmission electron microscope (TEM). The G0/G1 phase was arrested,typical apoptotic peak appeared, the apoptotic rate was 22.81％-38.54％ in three JLS granule-treated groups.Annexin V-FITC/PI double staining FCM assay showed that the apoptotic cells were 4.36％, 3.08％and 7.08％ in three dosages, most cells were localized in the low right quadrant.CONCLUSION: Jinlongshe granules possess anti-tumor effects on experimental tumor models in vivo, and apoptosis induction is one of its anti-tumor mechanisms.