Radioisotope renography was carried out in 564 cases consisting of 150 normal controls, 140 hypertensive, 102 hypertensive nephropathys, 62 chronic renal diseases, 53 unilateral, and 57 bilateral non-functioning kidneys. It was aimed to study which parameter of the renogram is most applicable to any definite disease of the kidney. The analytical methods adopted were;Tobe, Spencer, Krueger, Matchida and Takeuchi. In the non-functioning kidney groups, the hemograms and serum nitrogen series were also studied to evaluate the relationships between the renograms and renal anemia. The parameters were;time of maximum amplitude (Tmax), half-time of maximum amplitude (T¨ö), Kac value calculated from these two parameters in Tobe's method, slopes of B and C phase, B/A and B/C values in Spencer's method, total concentration (T.C.), minute concentration (M.C.) and minute excretion (M.E.) in Krueger's method, Matchida's K value and Takeuchi's renal function Index (R.F.I.). Following were the results:1) In general, marked differences in the patterns of the renogram were observed between the normal controls and nephropathys. In Tobe's method, each parameter showed statistically significant delay or decrease in patients with hypertensive nephropathys and chronic renal diseases. In Spencer's method, slopes of B and C phase and B/C, also showed the statistically significant decrease in patients with hypertension, hypertensive nephropathys and chronic renal diseases. In Krueger's method, M.C. and ME showed the statistically significant differences between the control and patients with hypertension, hypertensive nephropathys and chronic renal diseases, In Matchida's method, K value showed the statistically significant differences between the control and patients with hypertensive nephropathys and chronic renal diseases. 2) It appeared, therefore, that Tobe's T¨ö, Kac, Spencer's slopes of B and C phase, B/A, B/C values, Krueger's T.C., M.C., and M.E. values, matchida's K value are useful for the differentiation of various renal diseases, however, qualitative analysis of the renogram with one or two parameters is not accurate. 3) In bilateral non-functioning kidney groups, a positive correlation between anemia and nitrogen retention was observed, although the quantitative assessment of the degree of non-functioning was impossible.