Tumor necrosis factor-related apoptosis-induced ligand (TRAIL) is a promising antitumor therapy. However, many cancer cells, including malignant glioma cells, tend to be resistant to TRAIL, highlighting the need for strategies to overcome TRAIL resistance. Here we show that in combination with phenethyl isothiocyanate (PEITC), exposure to TRAIL induced apoptosis in TRAIL-resistant glioma cells. Subtoxic concentrations of PEITC significantly potentiated TRAIL-induced cytotoxicity and apoptosis in glioma cells. PEITC dramatically upregulated DR5 receptor expression but had no effects on DR4 receptor. PEITC enhances TRAIL-induced apoptosis through the downregulation of cell survival proteins and the upregulation of DR5 receptors through actions on the ROS-induced-p53.