This investigation was carried out to characterize and quantitate the collagen of rockfish intramusclar connective tissue. Different species ot rocktish were chosen to represent the range of product quality experienced by the fish processing industry. Species included widow, a rockfish noted tor its soft flesh, yellowtail, a rockfish possessing flesh of intermediatary texture and canary rockfish known for its firm flesh. The intramuscular connective tissue collagen was extracted from white muscle and total, salt, acid and insoluble collagen content was estimated by hydroxyproline analysis. No significant difference was observed among species with regard to all collagen fractions. Mean salt, acid and unsoluble collagen contents were 5.5 %, 8.7 % and 86 %, respectively indicating a relatively highly crosslinked and stable collagen compared to that reported for other fish collagens. The denatured acid soluble collagen traction was characterized by chromatography on CM-cellulose and the presence of three different alpha chains was established by SDS-polyacrylamide gel electrophoresis and amino acid analysis of the collagen components. The molecular weight for the alpha chains was estimated to be 96,000 based upon agarose molecular sieve chromatography. The alpha chains, designated αl, α2 and α3, had significantly different amino acid composition with the α3 chain possessing a higher level of hydroxylated lysine than αl and α2. In general, the amino acid composition of rockfish muscle collagen was similar to other reported fish collagens. Digestion of purified connective tissue and acid soluble muscle collagen with CNBr and subsequent analysis by LDS-polyacrylamide slab-gel electrophoresis showed identical peptide patterns indicating the presence of only one molecular type of collagen. This evidence along with the observed ratio of the collagen components resolved by CM-cellulose chromatography supported a molecular composition of αl-α2-α3 for rockfish muscle connective tissue collagen. Significant difference in skin thickness between species was observed. This correlated with the general quality ranking of the three species by the fish processing industry of canary>yellowtail>widow. Skin from canary rockfish was 38 % thicker than skin from widow rockfish while yellowtail had a skin of intermediatary thickness. From this observation, it was concluded that skin thickness and strength plays a more important role than intramuscular connective tissue characteristics in determining quality of product obtainable from the different rockfish species. / Graduation date: 1984