Data on synthesis, physicochemical properties, and functions of carotenoids in developing and dormant seeds are reviewed. During seed ripening carotenoids are involved in photosynthesis by performing light harvesting and protective functions specific of photosynthesizing tissues; they also serve as ABA precursors. In dormant seeds carotenoids are located in the plastids where they improve the structural integrity of membranes and protect nutrient substances against destruction. The role of carotenoids as lipophilic antioxidants is considered, and the mechanisms of carotenoidprotective action against free radicals produced during seed aging are discussed.