AIM To examine whether pretreatment with simvastatin protects the heart against free radical injury. METHODS 1 1 diphenyl 2 picryl hydrazyl (DPPH) was used for triggering free radical injury in cardiac tissue. Simvastatin against free radical injury was investigated in a Langendorff fused rat heart. Left ventricular developed pressure (LVDP), maximal velocity of increase of LVP (+d p /d t max ), heart rate (HR) coronary flow (CF) and malondialdehyde (MDA) formation in cardiac tissue were measured. RESULT In the DPPH free radical group, DPPH signficantly decreased LVDP, +d p /d t max , HR was slowed and CF was reduced. The formation of MDA was significantly enhanced. ( P