Carotenoid-binding proteins are commonly found in invertebrates. Their carotenoids form non-covalent complexes with proteins giving tissues a variety of colors. In molluscs they have been described in only a few species. In particular, the egg perivitellin fluid of those Ampullariid species which deposit eggs above the waterline is provided with carotenoproteins playing several roles ranging from photoprotection, antioxidant or antitrypsin actions to nutrient provision for development. These molecules form complex glyco-lipo-carotenoproteins of high molecular weight where either free astaxanthin (3,3'-dihydroxy-beta, beta'-carotene- 4,4'dione) or astaxanthin esterified with fatty acids, occur more frequently. This review compiles the current knowledge on the biochemical composition and biophysical data on the chemical and thermal stability of egg carotenoproteins in ampullariid. In addition, recent data on their metabolism, their cellular site of biosynthesis during perivitellogenesis, as well as their carotenoid binding properties are reviewed, highlighting the physiological significance of carotenoproteins in the context of the reproductive biology of these molluscs.