The use of the antineoplastic drugs cisplatin (cPt) and ifosfamide (IF) is limited by their nephrotoxicity. The aim of this study was to investigate whether cPt and IF specifically interact with the polyspecific basolateral organic cation transporter of the human kidney (hOCT2). The function of hOCT2 stably expressed in HEK293 cells was examined fluorimetrically with the cation 4-(4-(dimethyl-amino)styril)-methylpyridinium iodide (ASP, 1 mM) as substrate. Accumulation of cPt and IF was evaluated in lysates of hOCT2- or HEK293- cells after 10 min incubation at 37°C or 4°C. Platinum (Pt) was measured by atomic absorption-, IF by MS, and apoptosis (annexin V) by FACS. IC₅₀-values were 1.5 and 770 mM for cPt and IF. Pt accumulation was significantly higher in hOCT2- (0.55 ± 0.03 pg/cell, n = 3) than in HEK293-cells (0.15 ± 0.02 pg/cell, n = 3). Inhibition of metabolic processes at 4°C resulted in a reduction of cPt uptake (0.21 pg/cell, n = 2). IF accumulation was similar in hOCT2 and HEK293-cells. Incubation with cPt (100 mM, 15 hrs) induced a significant apoptosis in hOCT2- but not in HEK293-cells. Apoptosis was completely suppressed by contemporaneous incubation with the hOCT2 substrate cimetidine. These findings show that cPt and IF interact with hOCT2, but only cPt is transported by hOCT2. Therefore, hOCT2 is critically linked to cPt but not to IF nephrotoxicity. cPt-toxicity could be prevented by contemporaneous treatment with a competitor for hOCT2-transport.