Spices and herbs are recognized as sources of natural antioxidants and thus play an important role in the chemoprevention of diseases resulting from lipid peroxidation. Our studies on spices and herbs have given us over a hundred compounds, known and new, having high antioxidant activity. From the Labiatae family, Rosmarinus officinalis, Thymus vulgaris, Origanum vulgare and O. majorana gave 26 active comopounds. Over 40 antioxidative compounds from Zingiber officinale, 26 compounds from Curcuma domestica = C. longa, C. xanthorrhiza and Z. cassumunar were determined, these belonging to the family Zingiberaceae. From the family Myrtaceae, 25 compounds from the berries of Pimenta dioica were determined and 3 carbazoles were isolated from Murraya koenigii. Structure-activity relationships of some of the isolated compounds were also discussed.