This variation depends on the nature and the concentrationof the antioxidant used. A relatively high antioxidant activity isnoticed for rosemary extract and was estimated at 81% for a concentration of 0.08%. This activity was significantly better (p < 0.05) thanthat provided by BHT used at a concentration of 0.1% and which inhibits only 52% of free radicals. This shows that the preparedRE contains compounds which are responsible for a free radicalscapture and therefore could be used to stabilize and retard oil oxi-dation. This antioxidant activity can be attributed especially to thepresence of carnosic acid and carnosol previously identified in the RE