The purpose of the present study was to determine the effects of recombinant human interleukin-6 (rhIL-6) on the Bcl-2 and Bax expression and apoptosis after anoxia-reoxygenation in cultured rat hippocampal neurons. The control and rhIL-6 treated hippocampal neurons cultured for 12 d were exposed to anoxia environment (90% N2+10% CO2) for 2 and 4 h and then were reoxygenated for 24 and 72 h. The expression of Bcl-2 and Bax was revealed immunocytochemically using the antiserum against Bcl-2 and Bax. The apoptosis was examined by the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nickel end labeling (TUNEL) method and flow cytometric analysis. The results showed that in cultured hippocampal neurons the Bcl-2 expression decreased while Bax expression and the percentage of apoptotic neurons increased after anoxia-reoxygenation compared with those before anoxia. In comparison with the control, after anoxia-reoxygenation the Bcl-2 expression in hippocampal neurons was higher than that in rhIL-6 group; however the Bax expression and the percentage of the apoptosis were decreased in rhIL-6 group. It is suggested that rhIL-6 may play a role in protecting neurons from the damage induced by anoxia-reoxygenation.