Gray scale ultrasonography of the kidneys was performed in 30 patients with KHF, significant morphologic changes were noted representing the pathologic involvement of the kidneys, and aids in the clinical assessment of severity of the diseases. 1. Peak increased renal volume is seen in oliguric stage. 2. Renal cortical echogenicity is increased in oliguric stage, and returned to normal in convalescency. 3. Medullary pyramid enlargement is seen mainly in diuretic stage. 4. Retroperitoneal edema and thickening of renal capsule are noted in oliguric stage. 5. Abnormal fluid accumulation was seen in two-third of cases in the peritoneal and perirenal space only in oliguric stage. Renal sonography is simple, non hazardous modality, providing satisfactory infromation about the renal and retroperitoneal anatomy.