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Abstract Introduction: Human serum Albumin (HSA) is a single strand protein that plays a major role in the maintenance of plasma oncotic pressure. Surface of this protein is covered with unneutralized negative charges and has an important role in the transfer of some drugs , fatty acids , cations and hormones in the blood . Materials & Methods: HAS (Hexadesyl pridinium bromide ) was purchased from Sigma company and the other reagents were recieved from Merck Co. UsingPhosphate buffer in pH=7 for all experiments through CD- spectrophotometer (model Jasco) secondary structure changes in the protein were observed. The ligand binding of HSA- HPB interaction was studied by fluke potentiaometer. HSA concentration in all experiments was 0.2 mg/ml. Results: HSA CD spectra in the far – UV region were obtained at 370C and 420C . The binding isotherms and also scadchard curves for HAS-HPB interaction at 370C and 420C were drawn and discussed . Conclusion: Rising temperature from 370C up to 420C proved a considerable effect on the structural aspects of HSA. HSA- HPB interaction depends on the temperature so the affinity of HSA for HPB binding reduces as temperature increases to 420C from 370C . Therefore, the amounts of negative charges on the surface of HSA at the 420C are less then those at 370C and leads to the decrement of blood oncotic pressure. This effect expresses the considerable effect of HSA on the moderation of fever on the body.