A group of predicted structural similarities exist between the hydrophobic pulmonary surfactant protein SP-B and SP-C and the hydrophobic proteins of myelin, either the myelin basic protein and the proteolipid protein of central nervous system myelin, or the P0 protein of peripheral myelin. These similarities include, among other factors, the charge density, post-translational modification by fatty acids, some potential periodicity in primary structure and an overall hydrophobicity. The similarities suggest that these proteins might have similar means of interacting with each other and with lipid bilayers in their respective biological systems.