Abstract: Objective : To study the change of Caspase 8 activity in TRAIL-induced apoptosis of CHP212 neuroblastoma cells. Methods: The effects of TRAIL and Caspase 8 inhibitor zIETD-FMK+ TRAIL on the apoptosis of CHP212 cells were detected using flow cytometry. Relative Caspase 8 activ-ity was measured by colorimetric assay. Apoptotic cells were visually detected using a transmission electron microscope (TEM). Results : CHP212 cells were sensitive to TRAIL and this sensitivity was dose-dependent. The relative Caspase 8 activity in CHP212 cells increased gradually with prolonged exposure to TRAIL and with increased TRAIL concentration. The zIETD -FMK inhibitor could block the activation of Caspase 8 and diminish the TRAIL-induced apoptosis of CHP212 cells. Typical fea-tures of apoptosis were seen under TEM. Conclusion : TRAIL could induce the apoptosis of CHP212 cells through a Caspase 8 signal transduction pathway, with an increase in Caspase 8 activity.