The cytochrome P450 (CYP) is a group of enzymes that oxidatively modify drugs to a more water-soluble form for renal excretion. Nearly 50% of all clinically used medications and endogenous steroids are metabolized by the CYP enzyme 3A4, which explains why many of the important potential drug interactions involved this enzyme. Despite an excellent safety record, CYP 3A4 statins (lovastatin, simvastatin, atorvastatin) taken concomitantly with a potent CYP 3A4 inhibitor may increase the risk for adverse events (myopathy, rhabdomyolysis). This article describes the clinical significance of CYP metabolism as the pathways relate to the use of statins, including brief discussions on statins, fibrates, cyclosporine, and calcium channel blockers. In light of these potential interactions, continued vigilance by physicians is necessary to ensure the safe use of statins.