<p>This preliminary study investigates the thermal behavior of plasma and serum samples from seven patients with peripheral arterial disease treated with cilostazol using differential scanning calorimetry (DSC). Building on previous findings, which suggested a correlation between thermal unfolding of human plasma and cilostazol-induced walking improvement, this research seeks to explore differences in the thermal profiles of plasma and serum as potential markers of drug effects. A DSC examination of the serum was conducted on the same seven patients to extend the findings of the earlier plasma analysis. The plasma and serum DSC curves were analyzed to identify potential differences in protein stability and thermal behavior during treatment<b>.</b> DSC analysis demonstrated clear differences in the thermal profiles of plasma and serum, indicating that the distinct protein compositions of these blood components may respond differently to cilostazol treatment. The observed thermal unfolding patterns provide insight into the drug's potential impact on blood protein dynamics and interactions. This study contributes to preliminary insights regarding cilostazol therapy's influence on blood composition and may inform future strategies to optimize treatment outcomes in peripheral vascular disease.</p>