Experimental radiation nephritis was produced in 15 rabbits by X-irradiation. About $2,000{gamma}$ (tissue doses) were given to both kidneys of a rabbit in 5 days. Other tissues and organs except both kidneys were protected with 2mm thickened lead plates. 5 weeks after the last irradiation, blood pictures, blood pressures, B.U.N., serum creatinine, Ca, Mg, Fe levels and serum erythropoietin activity of the irradiated rabbits were studied. After finishing above studies, rabbits were sacrificed and both kidneys were removed and examined histopathologically. Same laboratory and pathological studies were performed in 6 control rabbits. In this study, the author obtained following results. 1) Both kidneys of rabbitis with experimental raditation nephritis showed marked histopathological changes, i.e.: renal tubules showed diffuse cloudy swelling, impacted intraluminal hyaline casts and focal precipitations of lime salts on the tubular epithelium. Diffuse interstitial fatty necrosis and various degrees of fibrotic infiltrations on the interstitium were also seen in association with focal lymphocytic infiltrations. Hyaline degenerations were observed on the glomeruli and small vessels. 2) Experimental radiation nephritis rabbits showed marked lowering in R.B.C. counts, decreased hemoglobin levels, low hematocrit values and leucopenia in comparison with those of control rabbits. (P<0.01). (Table 1 & 2). 3) Mild proteinuria were observed in experimental radiation nephritis in rabbits. 4) The levels of B.U.N. and serum creatinine increased in experimental radiation nephritis. (P<0.01). (Table 1,3 & 4) 5) The levels of serum Ca and Mg Showed no statistical difference in comparison with those of control rabbits. (P>0.05) (Table 3 & 4). 6) No statistical correlations were observable between the levels of B.U.N. and Hb. values. (${gamma}=-0.223$) No close correlations (${gamma}=-0.328$) were noticed between the levels of B.U.N. and serum iron levels. 7) Erythropoietin activity (R.B.C. $^{59}Fe$ Incorporation) was measured by the modified Fried method. No change in its activity was noticed in radiation nephritis group comparing with that of the control group. (P>0.05). (Table 1,3 & 5). 8) Carotid artery blood pressures showed also no difference. (P>0.05). (Table 1 & 2).