We report computed tomography (CT) and magnetic resonance (MR) findings of a patient with polyostotic Paget disease and multicentric giant cell tumor (GCT). Brain CT scan showed widening of diploic space, cortical thickening and enhancing soft tissue mass in occiput with underlying calvarial destruction. Ill-defined soft tissue masses were also detected in maxillary sinus and buttock with underlying bony destruction on CT. MR image showed multifocal nodules in wide diploic space with low signal intensity on T1 -weighted image and bright signal intensity on T2-weighted image. Mass in occiput showed homogeneous hypointensity to bone marrow on T1-weighted image and homogeneous iso- intensity on T2-weighted image. Multiple nodules in diploic space and occipital mass showed contrast enhancement following administration of Gd-DTPA. Biopsy was performed at scal p, maxillary sinus and buttock, and histologic analysis revealed GCT.