Gentamicin (GNT) is an aminoglycoside antibiotic used for treatment of serious infections, and the nephrotoxic adverse effect is one of the main therapeutic limitations. This study aimed to investigate the possible protective effect of apocynin (APO) on nephrotoxicity induced by GNT in rats. Twenty-four rats were allocated into three groups: control, GNT (100 mg/kg, intraperitoneally (i.p.)), and GNT plus APO (10 mg/kg, i.p.). All rats were killed at the end of the experiment, and then the blood, urine, and kidneys samples were taken. GNT-induced nephrotoxicity was manifested by a significant (p < 0.05) increase in the weight of kidney, 24-h urine volume, renal somatic index (RSI), protein in urine, serum lactate dehydrogenase (LDH), creatinine (Cr), blood urea nitrogen (BUN), renal Fas ligand (CD95), nitric oxide (NO), and malondialdehyde (MDA). Furthermore, a significant reduction in body weight, creatinine clearance (CCr), serum albumin, renal superoxide dismutase (SOD), and glutathione activities were detected when compared with the control rats. APO ameliorated the nephrotoxic effect and oxidative damage caused by GNT by improving tissue morphology and significantly decreasing 24-h urine volume, RSI, serum Cr, LDH and BUN, protein in urine, and renal content of MDA, CD95, and NO. Additionally, APO caused a significant elevation in renal SOD activity and CCr when compared with the GNT group. These results confirm that APO by its anti-inflammatory, antiapoptotic, and antioxidant effects can ameliorate GNT-induced nephrotoxicity.