Human serum paraoxonase 1 (PON1, EC3.1.8.1) is an important liver enzyme which is bound to HDL, contains calcium in its active site, hydrolyses organophosphate agents and nerve gases, has protective effect against the formation of lipid peroxides by oxidation of LDL and bacterial endotoxins. In our study, in order to purify the enzyme PON1, it was purified by hydrophobic interaction chromatography using sepharose-4B