Type II collagen is a homotrimeric molecule composed of three identical al(II) collagen chains that are synthesized as precursor procollagens with aminoand carboxy-terminal propeptides that are removed extracellularly. Mutati'ons in the ol(II) .chain result in disproportionate dwarfing disorders in the spectrum of skeletal dysplasias,' Hitherto, only the propeptides' sequences have been published.' Here, we report the isolation of the full-length al(II) cDNA and derived from it, the nucleotide sequence of the entire mature al(II) chain. The availability of these sequences will expedite the molecular characterization of other type II collagen disorders in the skeletal dysplasias.