Acid-soluble collagen (ASC) was extracted from the scales of lizard fish (Saurida spp.) and horse mackerel (Trachurus japonicus) from Japan and Vietnam. Collagen from horse mackerel scale in Japan had lower imino acid content (165 residues/1000 residues) than those from horse mackerel in Vietnam (175 residues/1000 residues). However, the imino acid content of ASC from lizard fish scale in Japan was little different from that of lizard fish in Vietnam (170 residues and 168 residues/1000 residues, respectively). The amount of imino acid is known to depend on the temperature of the environment in which the fish lives. The collagen from the fish species living in cold environments has lower contents of imino acid than those from fish living in warm environments since the imino acid content has direct correlation with thermal stability of collagen. The denaturation temperature (T_d) of collagen from horse mackerel scales caught in Japan (26.1⁰C) was lower than that of horse mackerel in Vietnam (28.1⁰C). However, the T_d of collagen from lizard fish scale inJapan andVietnam were little different may be due to their similar imino acid content to each other.