Cartilage cells from embryonic chick cartilage were grown in primary cultures. The cell layer was sequentially extracted with neutral saline, mercaptoethylamine and pepsin which revealed that these cells produced salt-soluble and salt-insoluble collagen. The alpha1- to alpha2-chain ratio was determined for the collagen extracted from the cultured cells and was found to be 13 to 1. Further analysis of the molecule was carried out by CNBr cleavage of the salt-extracted collagen and separation of resulting peptides by ion-exchange chromatography. It was shown that the cultured cartilage cells synthesize collagen of the type (alpha1[II])3.