Cryptococcus is a ubiquitous saprophytic fungus that may become pathogenic, particularly in immunosuppressed patients. In the CNS of AIDS patients, the incidence of this fungal infection is 5% of all the opportunistic infections. In this study, we review the MR findings in nine AIDS patients affected by CNS cryptococcosis. All MR studies were performed before and after intravenous administration of a single dose of gadopentetate dimeglumine and again after an additional dose. Autopsy was performed in one case. Magnetic resonance imaging revealed evidence of meningitis or meningoencephalitis, dilated Virchow-Robin spaces, cyst-like structures (gelatinous pseudocysts), and granulomas (cryptococcomas) of the choroid plexuses. The last two findings (pseudocysts and choroidal ependymal granulomas) are relatively specific for cryptococcosis.