The hydroxyproline (Hyp) content in two fish skins, squid skin and chum salmon skin, was determined by the spectrophotometric method and was shown to be 0.823% and 2.247%, respectively. The average recovery rates for the two skins were 98.47% and 98.39%, respectively, and the CV of Hyp from the two skins were 1.65% and 0.64%, respectively. This method can be used as a reliable method for the quantitative determination of the collagen in fish skins.