Cultured mouse neuroblastoma C1300 cells were examined for acid glycosaminoglycans using the Alcian Blue and periodic acid-Schiff staining techniques. It was found that the cells contained hyaluronidase-resistant sulphated glycosaminoglycans; hyaluronic acid, chondroitin sulphate, and sialoglycoproteins were not demonstrated. These properties are held in common with foetal mouse brain spongioblasts in culture. In contrast to the latter cells, but in common with some peripheral neuronsin vivo, C1300 cells were stained by the periodic acid-Schiff technique for neutral polysaccharides. The results are discussed in relation to the poor adhesive properties of neuroblastoma cells.