Size-exclusion chromatography (SEC) coupled to an inductively coupled plasma atomic emission spectrometer (ICP-AES) was employed to study the effect of the human serum albumin (HSA) concentration on the metabolism of cisplatin (CP) in human blood plasma in vitro. Plasma from 14 healthy adults and 11 pediatric cancer patients was spiked with CP and the Pt distribution was determined at the 5 min and 2 hr time point. The results revealed that as the HSA concentration decreased, the percent of Pt-bound to HSA decreased; whereas the percent of Pt-hydrolysis products increased, while other Pt-species were largely unaffected. These changes were corroborated by fortifying the cancer patient plasma with HSA to healthy concentrations followed by the addition of CP. In summary, these findings imply that the infusion of cancer patients with HSA to healthy plasma levels may decrease the fraction of free hydrolysis products, which may alleviate the severe toxic side effects of CP.