Nitric oxide (NO) induces apoptotic cell death in murine RAW264.7 macrophages. To elucidate the mechanism underlying the inhibitory effect of taurine on NO-induced apoptosis, a cell was exposed to sodium nitroprusside (SNP), an NO donor, in the absence and presence of taurine. Taurine treatment prevented SNP-mediated cellular apoptosis in a concentration dependent manner. The exposure of the cell to taurine prior to SNP treatment inhibited DNA fragmentation more than addition of taurine to the medium after SNP treatment. Agarose gel electrophoresis data revealed that taurine reduced the intensity of SNP-induced DNA laddering. The taurine-mediated reduction in the number of apoptotic cells was also observed using the Hoechst 33258 stain. These results support the idea that taurine has the potential to function as an inhibitory modulator of NO-mediated cell injury.