Internal architecture of an encapsulated hepatocellular carcinoma (HCC) was studied with magnetic resonance imaging and histologic correlation. The capsule of HCC showed low intensity relative to liver on both T1- and T2-weighted images. The T1-weighted images were superior to the T2-weighted images in delineating the capsule of HCC. The tumor showed a mosaic pattern, which was a configuration composed of multiple compartments of different intensities, reflecting viable tumor nodules and a necrotic portion. Viable tumor nodules, composed of trabeculae of polygonal cells resembling the normal liver cell with well-formed sinusoids, showed low intensity relative to liver on T1-weighted images and high intensity on T2-weighted images. The necrotic portion, composed of coagulation of amorphous, thick eosinophilic material without hemorrhage or inflammatory reaction, showed low intensity relative to liver on both T1- and T2-weighted images. The T2-weighted images were superior to the T1-weighted images in demonstrating the mosaic pattern of HCC.