Abstract: The Anti-rat albumin serum was prepared by immunized the sheep with rat albumin. A radioimmunoassay method was established for rat albumin. The measurement range of the assay was 1～50μg/ml, sensitivity of the assay was 0.12μg/ml, recovery rate was 97.8～108.4%.Intra- and inter-assay variation coefficients were <4.0% and <8.2% respectively. The correlation coefficients between measured and expected values were more than 0.990 after serial dilution of the urine samples with high concentrations of rat albumin. The kit for rat albumin might provide a convenience in exploitation of renal drugs and experimental injury of the kidney.