With redox-sensitive fluorescene probes DCFH-DA and DHR123, the formation of cytosolic and intramitochondrial reactive oxygen species (ROS) inside immature rat cerebellar granule cells during the apoptosis induced by nitric oxide donor S-nitroso-N-acetyl-pennicillamine (SNAP) was monitored by laser confocal scanning microscopy. The cytosolic and intramitochondrial ROS increase significantly after 0.5 mmol/L SNAP treatment for 1 h. Pre-treatment with the nitric oxide scavenger hemoglobin can effectively inhibit the formation of cytosolic and intramitochondrial ROS and protect neurons from apoptosis. Adding glutathione can also protect neurons from apoptosis, and the cytotoxity of nitric oxide increases significantly while the synthesis of glutathione is inhibited. The results indicated that ROS might be involved in NO-induced apoptosis in neural cells and glutathione might be the endogenesis antioxidant to protect neurons from oxidative injury.