The aim of this study was to determine the effect of marinating, cooking and storage on antioxidant activity of a very popular marinating sauce , namely green seasoning sauce (GSS). GSS was prepared and thermal treated at 204 ^oC for 40 min.. placing of untreated sauce on the surface of beef was occurred. Gross chemical composition, chemical indices of oil extracted from sauce, fatty acid composition and antioxidant activity (DPPH) were determined in sauce only and in sauce after marinating of beef 5 hours.           Acid value , free fatty acids , peroxide value and thiobarbituric acid of the sauce were increased after marinating and cooking at 204 ^oC for 40 minutes. Concerning to fatty acid composition , it was observed that palmitic and stearic acids were the predominant saturated fatty acids , while oliec and linoleic constituted about 32 and 47 % respectively. The saturated fatty acids were increased after marinating . Antioxidant activity of sauce was increased from 88.5 to 90.4 % after cooking , but the final thermal process after 5 hrs marinating led to a reduction of antioxidant activity . Also , the storage of sauce at 5±1 ^oC for 2-4 months  reduced  antioxidant  activity.