We have isolated and purified two unique glycoproteins from lung lavage material of patients with alveolar proteinosis. The same two glycoproteins with similar composition have been isolated from normal rabbit lung lavage material and lamellar organelle preparation. These glycoproteins are unique in that they contain collagen-like sequence in the peptide chain. Partial amino acid sequence analyses for these glycoproteins have confirmed this observation. The complete amino acid sequence analyses of these glycoproteins are underway to establish the extent of the collagen-like sequence in the peptide chain. The structures of the carbohydrate moieties of these glycoproteins have been established and found to be similar to the structures proposed for various mammalian glycoproteins. N-acetylglucosamine of the carbohydrate moiety was found to be attached to the asparagine of the peptide chain. Since these glycoproteins were found to be present in the lamellar organelle preparation of the normal animal lung, it was suggested that Type II cell of the alveolar might be the source of these glycoproteins. Type II cells have now been cultured in our laboratory and found to secrete the glycoproteins similar to those found in lung lavage material of patients with alveolar proteinosis as well as in normal animal.