Gold nanoparticles (AuNPs) have become the object of special interest due to their biomedical applications such as cell tracking, bio-sensing, contrast imaging, targeted drug delivery, and tissue engineering. The present study aimed to investigate the nephrotoxic potential of gold nanoparticles (20 nm) in Sprague-Dawley rats. Therefore, kidney functions were assessed in addition to oxidative stress and genotoxicity parameters. Moreover, histopathological examination was carried out. Adult female rats were divided into three equal groups of 20 animals each. Group (1) control group, animals were injected i.p. with physiological saline (0.9% saline) daily for 7 days, the other two groups were treated with 19.7 and 39.4 microgram AuNPs/kg.b.wt of 20 nm daily for 7 days: respectively. Blood and kidney tissue samples were collected from control and treated groups at four different time points (after 1, 3, 5, and 7 days from the start of the experiment) where five rats/groups were sacrificed at each time point. The results revealed that AuNPs exposure at 39.4 microgram/kg.b.wt significantly enhanced nephrotoxicity by increasing serum urea and creatinine levels from the 1st day till the end of the experiment compared to the corresponding control values and those of rats taken the therapeutic dose (19.7 microgram/kg.b.wt). Moreover, intraperitoneal injection of rats with AuNPs at the toxic dose 39.4 microgram/kg.b.wt) significantly reduced renal tissue GSH content and CAT activity (P<0.05) throughout the experiment with a marked increase of MDA production throughout the study when compared to control and low-dose groups. COMET assay showed that AuNPs exposure induced renal apoptosis which was exhibited through the recorded significant decrease in intact cells %, head diameter, and head DNA % in the double therapeutic dose of the AuNPs-treated group compared to the control and therapeutic dose of AuNPs-treated groups. The nephrotoxic effect of AuNPs was also confirmed by the observed renal histopathological alterations, especially at the high dose.