The present study examined pharmacokinetic profiles of KBP31705-Cl27 and KBP30603-901, new platinum coordination complexes synthesized as anticancer candidates, in comparison with two well-known platinum-containing anticancer agents, cisplatin and carboplatin in rats. Under sodium pentobarbital anesthesia of male Sprague-Dawley rats, urinary bladder, and femoral artery and vein were catheterized for urine collection, blood sampling and drug injection, respectively Following i.v. administration of cisplatin (2 mg/kg), KBP31705-C127 (2 mg/kg), carboplatin (20 mg/kg) or KBP30603-901 (20 mg/kg), blood samples were collected at 2, 4, 6, 8, 10, 15, 20, 30, 45, 60 and 120 minutes. Urine samples were collected at 1-hr interval for 4 hr. Platinum concentrations in plasma and urine were measured using an inductively coupled plasmamass spectrometer. The plasma concentration-time curves were biphasic for all drugs during the time period studied. Compared with cisplatin, KBP31705-C127 showed similar decay patters in the alpha- and betaphases with slightly lower plasma concentrations. Urinary platinum excretion for cisplatin and KBP31705-C 127 was 56 and 52% of the administered dose in 4 hr, respectively. With regard to carboplatin and KBP 30603-901, a similar decay pattern was also observed in the alpha-phase. The half life of KBP30603-901 in the beta-phase, however, was much longer than that of carboplatin, which was consistent with the urinary excretion results that 46 and 59% of the administered dose were excreted in the urine in 4hr, respectively. The results suggest that platinum coordination complexes are primarily excreted via the renal route and KBP30603-901 can elicit longer duration of action due to slower renal excretion compared to carboplatin.