Objective Diallyl disulfide ( DADS) has achieved remarkable effects in treatment and research of diverserfied cancers.The article was to explore the effects and the mechanism of DADS on the xenograft growth of human small cell lung cancer ( SCLC) cells in nude mice . Methods A total of 25 nude mice were selected to establish xenograft model of NCI-H446 human SCLC cells.The nude mice bearing with SCLC H446 were divided into 5 groups by random selection:positive control group(DDP 66 mg/kg), negative control group(physiological saline), 20 mg/kg DADS group, 60 mg/kg DADS group and 180 mg/kg DADS group, which is 40.6%, 53.1%and 66.4%, respectively.The growth of xenograft tumor in mice was observed after being treated with differ-ent concentrations of DADS .The morphological changes of the tumors were examined under light microscopy .Phase distribution and apoptosis of xenograft cells were analyzed by flow cytometry ( FCM) . Results The growth of xenograft tumor were inhibited signifi-cantly by DADS, resulting in decreased cell density and cellular atypia .Moreover, xenograft cell cycle was blocked in G 2/M and cell apoptosis rate was enhanced . Conclusion DADS can significantly inhibit the growth of NCI-H446 cells and lead to apoptosis .