Conclusion: It is thought that oxidative stress may be the major cause of the increase in the oxide thiol form in the study group. The relationship between oxidative stress status and dynamic thiol/disulphide in nasal polyposis now needs to be investigated.Objectives: The purpose of this study was to evaluate the relation between nasal polyposis and thiol/disulphide homeostasis, used as a marker of oxidative stress, by measuring that exchange using a novel technique.Materials and methods: The study group consisted of 40 patients (mean age=46.7513.92 years) with bilateral nasal polyposis patients admitted to the hospital. The control group consisted of 31 (mean age=43.20 +/- 5.68 years) age, sex, and body mass index matched healthy subjects. Thiol/disulphide homeostasis concentrations were measured using a newly-developed method (Erel & Neselioglu).Results: Native thiol and total thiol levels were lower in the study group compared to the control group (native thiol=415.8 +/- 69.1mol/L vs 448.7 +/- 37.5mol/L, p<0.05; total thiol=449.02 +/- 72.0mol/L vs 477.28 +/- 44.5mol/L, p< 0.05, respectively). Disulphide level and the disulphide/native thiol and disulphide/total thiol ratios were higher in the study group compared to the control group (disulphide=16.58 +/- 5.04mol/L vs 14.28 +/- 5.3mol/L, p <0.05; disulphide/native thiol ratio=4.07 +/- 1.52% vs 3.14 +/- 1.04%, p<0.05, disulphide/total thiol ratio=3.73 +/- 1.23% vs 2.94 +/- 0.92%, p<0.05, respectively).