Aspirin (ASA) is one of the most widely used nonsteroidal anti-inflammatory drugs. ASA has primarily been used to treat headaches, rheumatic pain, and inflammation, but its therapeutic effects have recently been demonstrated on a range of disorders, including those of the central nervous system. In this study, we investigated whether ASA is neuroprotective in inflammation-mediated neurodegenerative diseases. Pretreatment with ASA reduced the lipopolysaccharide (LPS)-induced degeneration of dopaminergic (DA) neurons in mesencephalic neuron-glia cultures in a dose-dependent manner. The neuroprotective effect of ASA was attributed to the inhibition of microglial activation because of its observed inhibitory effects on LPS-stimulated nitric oxide, tumor necrosis factor-α, and superoxide production by microglial cells. Moreover, ASA increased the production of the anti-inflammatory cytokines transforming growth factor beta-1 and interleukin-10 in neuron-glia cultures after stimulation with LPS. Mechanistic studies revealed that the neuroprotective effects of ASA were mediated through the inhibition of nicotinamide adenine dinucleotide phosphate oxidase (PHOX), a key enzyme for superoxide production in microglia. These results suggest that ASA protects DA neurodegeneration by inhibiting the microglial-mediated oxidative stress/inflammatory response and by regulating the production of anti-inflammatory cytokines.