We investigated the thiol-redox state, and the relationship between structural characteristics, such as thermal stability, and functional properties, such as cell growth activity, of commercial plasma-derived (pHSA) and recombinant human serum albumin (rHSA) products. In this study, 5 pHSA products (A1653, A9511, A1887, A8763, and A3782) and 2 rHSA products (A9731 and A9986) were obtained from Sigma-Aldrich. Among them, three kinds of HSA products [A1653 (an initial fractionation product), A3782 (a final purified product), and A9731 (recombinant albumin expressed in rice)] were selected for experiments on the thermal stabilities, analyzed by thermal denaturation curves, and cell growth activities of U937 and THP-1 cell lines using the WST-1 reagent. The secondary and tertiary structures of HSA products were similar, whereas a marked difference was observed in their thermal stabilities. The degree of thermal stability of the three representative products was in the order of A9731 (rHSA)>A1653 (pHSA)>A3782 (pHSA), as was the degree of cell growth activity of these products. One possible explanation for the present results is that albumin-bound fatty acids may have influenced the thermal stabilities and cell growth activities of U937 and THP-1 cells.