Parameters of oxidative stress, microsomal cytochrome P450 activity and peroxisomal fatty acid oxidation were studied in liver of rats following acetone (1% v/v) consumption for 7 days. Acetone treatment increased the activity of catalase and decreased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GTPx), but did not significantly modify the liver content of malondialdehyde (MDA) and reduced glutathione. Also, acetone increased the total content of cytochrome P450, the microsomal lauric acid hydroxylation, aminopyrine N-demethylation and the peroxisomal beta-oxidation of palmitoyl CoA. These effects were similar to those found previously in starved and ethanol-treated rats, supporting the hypothesis that ketone bodies would be the common inducer of microsomal and peroxisomal fatty acid oxidation in these metabolic states.