After treatment of PC12 cells with various doses of dopamine (DA), the apoptotic cells were observed with TdT-mediated dUTP nick end labelling method (TUNEL) and DNA gel electrophoresis. Meanwhile, Bcl-2, Bax and cytosolic cytochrome c as well as cleaved caspase-3 P₂₀ were detected with Western blotting assay. The results showed that during the process of DA-induced apoptosis, the cleaved caspase-3 P₂₀ and the release of cytochrome c into cytosol were elevated markedly compared with the controls. The protein levels of Bcl-2 were decreased, however, Bax protein was increased significantly. After pretreatment of PC12 cells with cyclosporine A at 1 μmol/L for 24 h, the release of cytochrome c and caspase-3 activation were blocked almost. But it didn't show effect on protein levels of Bcl-2 and Bax. The results suggested that Bcl-2 family and cytochrome c and caspase-3 might be involved in the progression to apoptosis induced by DA, furthermore, the release of cytochrome c from mitochondria might be an essential event.