A review. It is necessary to intensity magnetic resonance images of brain and spinal marrow tumors by means of contrast agents. As those paramagnetic substances may be used. There are two groups of paramagnetic contrast agents: substances with paired electrons, that is some bivalent metals, and substances with unpaired electrons-stable free radicals. To reduce metals toxicity they are usually applied as complexes, more often with chelating agents. In some cases liposomal contrast agent are preferential.