We retrospectively reviewed magnetic resonance image findings of the primary CNS lymphomas in six patients. All patients showed parenchymal masses (n=8), a solitary mass in 4 and multiple in the other two. One patient showed leptomeningeal lesion. Parenchymal masses were located in forntal lobe (n=4), cerebellum (n=2), basal ganglia (n=1), and parietal lobe (n=1). These masses showed hypointensity on T1- weighted images (WI). On T2 WI, the signal intensity of mass was isointense to the brain parenchyma in 5 and hyperintense in 3. After Gadolinum-DTPA injection, seven lesions were enhanced homogeneously, and the margin of the mass was smooth in 5 and irregular in 3. Peritumoral edema was moderate in 4, absent in 3, and severi in 1. These characteristics may be useful in the diagnosis of primary CNS lymphoma.