In this report, the temporal sequence of myopathology during a clofibrate-induced muscular syndrome and its recovery in rats is described using histopathologic, histochemical and electron microscopic technics. Two stages of myopathology are described: an early stage characterized by myopathic features, and a later stage characterized by neurogenic features. Although muscle histology returns to normal after 1 week of discontinuing the drug, electron microscopic abnormalities persist through the second week. It is proposed that clofibrate, in addition to its myotoxic effect, may be neurotoxic.