In order to investigate the effects of microwave on the dynamic changes of phagocytic function and Milk Fat Globule Factor-E8 (MFG-E8) expression in microglia, N9 microglial cells were irradiated with a 20-min exposure to 60 mW/cm2 pulsed microwave or a sham treatment. TNF-α and NO were measured using enzymelinked immunosorbent assay (ELISA) and the nitrate reductase method, respectively. Microglial marker CD11b and the bridging molecule, MFG-E8 was assessed via immunoreaction. Expression of MFG-E8 protein was evaluated by western blotting. CD11b positive N9 cells were significantly increased at 3 h and 12 h (p<0.05). The secretion of TNF-α and NO were significantly increased at 1 h after microwave exposure (p<0.05), then maintained at a high level for 24 h. Phagocytic function was enhanced at 3 h and 6 h after microwave exposure (p<0.05), then decreased, even lower than the sham group at 12 h (p<0.05). The expression pattern of MFG-E8 was similar with the phagocytic func-tion. These results indicate that microwave can obviously activate microglia, the ability of the phagocytiosis of apoptotic cells is increased first, and then decreased in the over-activated microglia. MFG-E8 expression pattern may be responsible for the radiation-induced change of microglial phagocytosis.Cited