The present study was performed to evaluated the pathological effects of tiaprofenic acid (surgam) on the kidneys of adult male albino rat and the possibility of recovery after stoppage of the drug administration. 40 male albino rats divided into 4 equal groups were used in this study. Group I: (the control group) the animals were intramuscularly injected with 0.5 ml physiological saline solution. Group II, the animals were intramuscularly injected with the therapeutic dose of tiaprofenic acid (TA) (18 mg/kg b.w.) every 12 hours for 2 weeks. Group III, the animals were intramuscularly injected with double the therapeutic dose of (TA) (36 mg/kg b.w.) every 12 hours for 2 weeks. Group IV, the animals were intramuscularly injected with double the therapeutic dose of (TA) (36 mg/kg b.w.) every 12 hours for 2 weeks and then left without treatment for 4 weeks for the possibility of recovery. Animals of groups I,II,III were sacrificed 24 hours after the last dose, while animals of group IV were sacrificed 4 weeks after the last dose, and the kidney samples were obtained and processed for histological and ultrastructural examinations. Histological changes in the rat kidney induced by tiaprofenic acid (TA) included hypertrophied glomeruli, swelling of the parietal epithelial cells, proliferation of the mesangial cells, and narrowing of the urinary spaces. Moreover, the cells of the proximal and distal convoluted tubules showed marked cloudy swelling with hypertrophied nuclei ; some displayed signs of pyknosis and karyolysis. Many inflammatory cells invading the intertubular spaces were also seen.Ultrastructural observations revealed swollen of the parietal epithelial cells of Bowman's capsules , narrow urinary spaces, focal fusion of the visceral epithelial cells, thickened glomerular basement membrane and dilated glomerular capillaries with the prescence of amorphous materials as well as blood cells in the capillaries lumina. The proximal convoluted tubules showed erosion of the microvilli constituting the brush borders, with cell debris or cast in the lumina of the tubules; besides, degenerated mitochondria and lysosomes, fragmented rough endoplasmic reticulum and destruction of the basal infoldings were observed. The epithelial cells of the distal convoluted tubules manifested marked loss of some basal infoldings as well as degenerated mitochondria, and destructed endoplasmic reticulum. However, in the recovery group there was marked improvment in the kidney tissues which appeared more or less normal.