Mitochondrial dysfunction is a basic mechanism leading to drug nephrotoxicity. Replacement of defective mitochondria with freshly isolated mitochondria is potentially a comprehensive tool to inhibit cytotoxicity induced by ifosfamide on renal proximal tubular cells (RPTCs). We hypothesize that the direct exposure of freshly isolated mitochondria into RPTCs affected by ifosfamide might restore mitochondrial function and reduce cytotoxicity. So, the aim of this study was to assess the protective effect of freshly isolated mitochondrial transplantation against ifosfamide-induced cytotoxicity in RPTCs. Therefore, the suspension of rat RPTCs (106 cells/ml) in Earle’s solution with the pH of 7.4 at 37°C was incubated for 2 h after ifosfamide (4 mM) addition. Fresh mitochondria were isolated from the rat kidney and diluted to the needed concentrations at 4°C. The media containing suspended RPTCs was replaced with mitochondrial-supplemented media, which was exposed to cells for 4 hours in flasks-rotating in a water bath at 37°C. Statistical analysis demonstrated that mitochondrial administration reduced cytotoxicity, lipid peroxidation (LPO), reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP) collapse, lysosomal membrane damage, extracellular oxidized glutathione (GSSG) level, and caspase-3 activity induced by ifosfamide in rat RPTCs. Moreover, mitochondrial transplantation increased the intracellular reduced glutathione (GSH) level in RPTCs affected by ifosfamide. According to the current study, mitochondrial transplantation is a promising therapeutic method in xenobiotic-caused nephrotoxicity pending successful complementary in vivo and clinical studies.