The accumulation of ROS resulted from the activation of the enzymatic activity of NADPH oxidases (NOX) elevates the cytosolic Ca2+ concentration [Ca2+]c causes cell death through the activation of poly-ADP-ribose(ADPR) polymerase (PARP). ROS-dependent PARP-1 activation has been act as the main mechanism in promoting ADPR generation resulting in the activation of the transient receptor potential melastatin-related 2 (TRPM2) channel, a Ca2+-permeable channel. In this present studies, we have provided compelling evidences using both pharmacological and genetic approaches to demonstrate that the microglial TRPM2 channel plays a critical role in mediating ROS-induced microglial cell death. Measurements of the [Ca2+]c showed that H2O2 induced robust increases in the [Ca2+]c in a concentration-dependent manner and such Ca2+ responses were strongly inhibited by pretreatment with PJ-34, a PARP inhibitor, and also by pretreatment with 2-APB, a TRPM2 channel inhibitor. Indeed, H2O2-induced Ca2+ responses were largely decreased in microglial cells isolated from trpm2-/- mice. H2O2 applied at 30-300 µM induced concentration-dependent microglial cell death and H2O2-induced cell death was significantly attenuated by pretreatment with 10 mM IM-54 from 90%±2.1 % to 55%±8%, suggesting microglial cell death preferentially via the necrotic mechanism. H2O2-induced cell death was significantly decreased from 91%±2.5 to 57%±4, 59%±10 and 18%±6% by pretreatment PJ-34, DPQ and 2-APB respectively. In fact, a significant reduction in microglia cell death was seen in TRPM2-dificient microglial compared to WT which was about 16%±3.6% and 99%±0.6% respectively. Zinc at 300 µM caused necrotic cell death in microglial cells (3%±1% vs. 89%±4%) and this response was significantly inhibited by NOX inhibitors, DPI and GKT 137831, from 88%±5 to 44%±12% and 32%±3% respectively. Furthermore, immunofluorescence studies showed a strong inhibition by PJ34 or DPQ in the increases of the PAR level induced by Zn2+ and H2O2, but treatment with DPI or GKT attenuated the increases in the PAR level induced by Zn2+ but not by H2O2. Consistently, treatment with PJ34 and DPQ strongly inhibited Zn2+-induced cytotoxicity (91%±1.1% vs. 30%±3.8% for 10 mM PJ-34 and 42%±3.6% for 10 mM DPQ). Zn2+-induced cell death was significantly attenuated by pretreatment with 2-APB (90%±1.1% vs. 32%±3.9%) and TRPM2 channel deficiency (93%±1.9% vs. 17%±3.8% at 300 mM Zinc for WT and KO-TRPM2 respectively). Taken together, these results provide clear evidence to support that activation of the TRPM2 channel is a key molecular mechanism responsible for ROS-dependent Zn2+-induced microglial cell toxicity.