Protein kinase C (PKC) activity was measured in samples of neocortex, cerebellum, and hippocampus from adult rats receiving a series of 10 electroconvulsive seizures (ECS). Rats were sacrificed immediately and at various intervals from 15 min to 24 h after the last seizure. From 77 to 84% of total PKC activity was found in the cytosol versus the membrane fraction. PKC activity in cerebellum was significantly higher than in neocortex (15%, P less than 0.05). Repeated ECS treatment did not affect total PKC activity nor its distribution between membrane and cytosolic fractions when compared with sham ECS controls. This finding is in keeping with reports that adrenergic-stimulated phosphoinositol turnover is not altered 24 h following repeated ECS.