The present study investigates the toxicity of t-butyl hydroperoxide (t-BuOOH) in cultured rat cortical neurones and astrocytes. Both neurones and astrocytes were destroyed by exposure to t-BuOOH in a time- and concentration-dependent manner. Astrocytes were more resistant to destruction by hydrogen peroxide (H2O2) than neurones, but there was no difference in susceptibility to t-BuOOH between neurones and astrocytes. The toxic effect of t-BuOOH was significantly blocked by antioxidants, propyl gallate and trolox, but not by superoxide dismutase nor by H2O2-scavengers, catalase and 4-nitrophenylglyoxylic acid. These results suggest that t-BuOOH toxicity is caused by oxidative stress unrelated to superoxide and H2O2. In addition, the toxic effect of t-BuOOH was attenuated by the presence of iron chelators, deferoxamine and N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine, indicating the requirement of endogenous iron for t-BuOOH toxicity.