The patterns of renogram in patients with Korean hemorrhagic fever were evaluated with clinical course and renal hemodynamic changes in various clinical stages. The renal plasma flow was measured by hippuran blood clearance using $^{131}I$-ortho-iodohippurate and hippuran renogram was analysed by means of quantitative and qualitative methods in 26 patients of Korean hemorr hagic fever. The results obtained with this study were as follows; 1. During the oliguric phase of Korean hemorrhagic fever, the renogram showed non-functioning (flat) or obstructive pattern. The group of patients with non-functioning pattern of renogram had more severe impairement of renal function and grave prognosis than the group with obstructive pattern of renogram. 2. During the diuretic phase, the renogram showed obstructive or dysfunction or normal pattern, which was related with the recovery of renal function. Obstruction pattern of renogram was observed till the 2nd week of diuretic phase. Normal pattern of renogram began to appear by the 2nd week of diuretic phase. 3. During the convalescent phase of Korean hemorrhagic fever, 40% of patients showed dysfunnction pattern of renogram, and the recovery of abnormal renogram in Korean hemorrhagic fever was more delayed than the recovery of clinical features and laboratory findings. 4. The renogram showed normal pattern 6 months after onset of Korean hemorrhagic fever in all cases. 5. There was significant correlationship between the pattern of renogram and the decreace of renal plasma flow in the patients with Korean hemorrhagic fever. The decreace of renal plasma flow was maked in the patients with non-functioning pattern of renogram and was least in the patients with dysfunction pattern of renogram. All above results suggested that the renogram reflects the effective renal plasma flow and degree of renal impairement, and the renogram may be one of the important indexes which could give us a more precise prognosis in Korean hemorrhagic fever.