Garlic (Allium sativum L.) is widely used as an obligatory part in many cooked dishes loosing during this process a certain part of its bioactivity. Antioxidant capacity measured by the ferric-reducing/antioxidant power (FRAP) method and by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical assay was the highest in raw and in a short time processed garlic samples by cooking. 70 Wistar rats were randomly divided into 10 diet groups, each of seven. They were named Control, NPG, PG1, PG2, PG3, Chol, Chol/NPG, Chol/PG1, Chol/PG2 and Chol/PG3. The rats of the Control group were fed basal diet (BD), which included wheat starch, casein, soybean oil, cellulose, mineral and vitamin mixtures. To the BD of the nine other groups were added 25mg of lyophilized non processed garlic equivalent of 500 mg non processed garlic/kg body weight (NPG), the same quantity of processed garlic for 20, 40 and 60 min for PG1, PG2 and PG3, respectively, 1% of cholesterol (Chol), 1% of cholesterol and 25mg/kg body weight of lyophilized non processed garlic (Chol/NPG), 1% of cholesterol and the same quantity of processed garlic for 20, 40 and 60 min for Chol/PG1, Chol/PG2 and Chol/PG3, respectively. The dose of 500 mg (25mg of lyophilized garlic/kg body weight) was chosen as the most effective (Banerjee, S.K., Maulik, M., Mancahanda, S.C., Dinda, A.K., Gupta, S.K., Maulik, S.K., 2002. Dose-dependent induction of endogenous antioxidants in rat heart by chronic administration of garlic. Life Sciences 70, pp. 1509-1518). Plasma lipid profile and the total antioxidant capacity in rats significantly differed in diet groups with addition of garlic samples cooked for a long time. In summary, garlic cooked for a short time preserves a high bioactivity of non processed garlic. The diet supplemented with these samples and cholesterol improved lipid indices, decreased fibrinogen and increased antioxidant activity in plasma of rats. Therefore, for preservation of garlic bioactivity optimal regime has to be used.