In the last 10 years, the use of intravenous contrast media in magnetic resonance (MR) has become well-established clinical practice. Contrast media provide critical additional diagnostic information in many instances. The gadolinium chelates constitute the largest group of MR contrast media and are considered to be very safe. These agents are thought to be safer than nonionic iodinated contrast agents. Unlike x-ray agents, the gadolinium chelates are not nephrotoxic. Minor adverse reactions, including nausea (1%-2% for all agents) and hives (<1% for all agents), occur in a very low percent of cases. Health care personnel should be aware of the (extremely uncommon) potential for severe anaphylactoid reactions in association with the use of MR contrast media and be prepared should complications arise. The four gadolinium chelates currently available worldwide, gadopentetate dimeglumine, gadoteridol, gadodiamide, and gadoterate meglumine, cannot be differentiated on the basis of adverse reactions. Far fewer patients have been examined to date with the two other agents that have widespread approval, mangafodipir trisodium and ferumoxides. These latter two agents are considered to be very safe but have a higher percentage of associated adverse reactions (7%-17% with mangafodipir trisodium and 15% with ferumoxides). This review discusses the safety issues involved with administration of intravenous contrast media in MR imaging, focusing on the six agents (four gadolinium chelates, one manganese chelate, and the last a large iron particle) with widespread use world-wide.