Cross-sectional imaging is playing an increasing role in diagnosis of diffuse liver diseases because it clarifies, in many cases, the overlap in clinical and laboratory manifestations often present in diffuse hepatic processes and thus may eliminate the need for a biopsy. Advances in cross-sectional imaging, particularly in magnetic resonance (MR) imaging, enable further characterization of hepatic parenchymal and architectural changes, allowing closer correlation with underlying pathologic changes. Advanced imaging techniques can be used to characterize a variety of metabolic, vascular, toxic, infectious, and neoplastic diffuse liver diseases. These include more common entities such as cirrhosis, Budd-Chiari syndrome, hemochromatosis, Wilson disease, fatty change, and diffuse neoplastic disease (hepatocellular carcinoma, metastasis, and lymphoma) and uncommon entities such as schistosomiasis, sarcoidosis, and amyloidosis. Correlation of computed tomographic and MR imaging findings with underlying pathologic features is helpful in understanding the gamut of diffuse diseases of the liver.