Magnetic resonance (MR) contrast agents are increasingly being used to help detect and characterize various neoplastic, inflammatory and functional abnormalities. The extracellular, non-specific contrast agents gadolinium chelates are by far the most widely used. Over the past few years a number of MR organ specific contrast agents have been introduced. MRI contrast agents are generally safe and well tolerated. The present review summarizes the properties, main characteristics and imaging applications of commercially available compounds as well as safety of these agents in normal and high-risk patients.