We investigated the effects of the early phase of sepsis and prior treatment of Simvastatin on muscle structure and mitochondrial enzymes treated with lipopolysaccharide (LPS) in rats. We divided rats into control, LPS, simvastatin, simvastatin + LPS groups. Mitochondrial citrate synthase, complex I, II, I + III, II + III, cytochrome c oxidase (COX) activities were measured. Muscle tissue was stained using modified Gomori trichrome (MGT), succinic dehydrogenase (SDH) and cytochrome oxidase (COX). In all treated groups, complex I and citrate synthase activities were higher than in the controls. In the control and LPS groups, COX activity was increased when compared with simvastatins'. Complex II, II-III activities were higher in the LPS group than in the control group. Complex I-III activities were higher in the Simvastatin and Simvastatin + LPS groups than in the control and LPS groups (P < 0.05). Myopathic changes with LPS group were observed in MGT stained sections. Our findings showed improvements in the alterations of enzyme activities and muscle myofibrils after treating rats with LPS that had received a prior dose of simvastatin.