Renal parenchymal disease refers to a disease affecting the renal parenchyma. It also includes the systemic diseases, which involve the kidneys. Renal parenchymal diseases can be classified into three categories: glomerular, tubulointerstitial, and vascular diseases. For radiological evaluation, the most useful morphological criteria include renal size, contour, and laterality of involvement. Although the diagnosis of renal parenchymal diseases still largely depends upon renal biopsy, imaging studies have important roles in the evaluation of patients. A plain radiograph may offer renal size and the presence of parenchymal calcifications. Ultrasonography (US) is often the first-line imaging modality for the evaluation of renal parenchymal diseases. The change in renal parenchymal echogenicity is the most commonly used clue. Doppler US is a technique for the evaluation of renal blood vessels and the hemodynamic changes of the kidney. The role of CT and MRI in renal parenchymal disease is limited but may be useful in selected cases.