The toxic effects of different doses of diclofenac sodium (DS) on the kidney on the postnatal period (0-7 days) by morphometrical and immunohistochemical methods were investigated. For this purpose, 15 female adult wistar albino rats were used and divided into 5 main groups. Group Ia served as normal control, physiologic group Ib received normal saline, group II received low dose (3.9 mg/kg), group III received medium dose (9 mg/kg) and group IV received high dose (18 mg/kg). Male offspring's from 0-7 days after birth were used in this study. On the 8th day of postnatal life, all animals were anesthetized. Then, the kidney samples were analyzed. Haematoxylin and eosin staining showed degeneration and necrosis, apparent atrophy of the glomeruli, mononuclear cell infiltration, congested vessels, increased fibrous tissue and distortion of the proximal convoluted tubules with interruption of the brush margin of the DS treated group. Increased level of Caspase-3 and upregulation of TNF-alpha with different doses of DS. In light of our findings, DS may lead to adverse effects that are dose-dependent in the prenatal subjected kidney to this drug.