Objective To investigate the effects of diallyl disulfide (DADS) on ceil proliferation in human small cell lung cancer H446 cells in vitro. Methods MTT assay was used to observe inhibitory effect of DADS on proliferation of H446 cells. Cell Proliferation in-hibition was measured by growth curve analysis, average doubling time, vitality detection and MT]" assay. Cell morphology was observed by inversion microscope and optics microscope. Cell apoptosis was analyzed by cell morphology observed under light microscope, flow cytometry (FCM). Results MTT assay showed that DADS from 4 to 60 μg/ml significantly inhibited t446 ceils and exhibited a dose-dependent and time-dependent model. After exposure to DADS, H446 cell average doubling time retarded from 25. 40 hours to 145. 64 hours( P＜0.05).Flow cytometry analysis revealed that the cell content of C0-phase declined, however, hypodiplod peak was increased, which means cell ap-optosis were induced by DADS. Conclusion DADS could significantly inhibit the proliferation of H446 cells and induce the apoptosis of H446 cell.