This study investigated the effects of di–n–butylphthalate on the kidneys after oral administration, to adult male albino Wistar rats. Twenty rats, weighing between 146.10g and 301.20g were arranged into groups A,B,C,D, of five rats each, and were fed with graded concentrations, 0 mg/kg, 2,000 mg/kg, 4,000 mg/kg and 6,000 mg/kg body weight of di–n–butylphthalate respectively for thirty days. Serum urea and creatinine levels were used as test of renal function, In addition, the cell histology of the kidneys of the rats were also examined. There were significantly higher levels (P < 0.05), of creatinine and urea in groups B (71.80 ± 1.43µmol/L, (3.44 ± 0.10Mmol/L), C (85.40 ± 1.47µmol/L, 4.70 ± 0.18Mmol/L), and D (108.00 + 0.95µmol/L, 6.30 ± 0.13Mmol/L), when compared with the control group A. The histological examination of the kidney in groups B, C, and D indicated glomerular expansion, generalized inflammation of some glomeruli and vascular congestion, After thirty days of treatment, the control group showed a mean weight gain of 1.31%, whereas the treated groups B, C and D recorded a significant decrease in weight of 2.02%, 2.11% and 1.19% respectively. This study indicates that the chemical, di–n– butylphthalate is organotoxic, and may affect kidney functions rats at high concentrations