The compositions and states of neutral sugars in several invertebrate collagens were investigated. The invertebrate collagens studied were obtained from squid, octopus, abalone, clamworm (annelid worm), spiny lobster, and blue crab. In general, these collagens were rich in neutral sugar as compared with most vertebrate collagens and its content varied from 3-4% in molluscan collagens, 5-6% in annelid collagens and to more than 10% in arthropod collagens. In all the collagens except for annelid cuticle collagen, about 85-95% of the total sugar was accounted for by comparable amounts of glucose and galactose, where most of the galactose was found to be in hydroxylysine-linked carbohydrate units. The glycosylated hydroxylysines, Glc-Gal-Hyl and Gal-Hyl, were determined by the improved method of ion-exchange chromatography. These glycosylated hydroxylysines were distributed widely and in considerable amounts in these invertebrate collagens excepting the annelid cuticle collagen which lacked the glycosylated hydroxylysines. Their contents varied from 6-8 residues/1000 in molluscan and annelid intestine collagens to 20-25 residues/1000 in arthropod collagens. More than 90% of the glycosylated hydroxylysines in all the collagens was present as Glc-Gal-Hyl.