1. 1. The collagen content in the abdominal muscle of seven species including shrimp, prawn, lobster and squilla varied among the species ranging from 1.1 to 6.2% of total tissue protein and the content in pereiopod and thoracic muscles of four species of crab varied ranging from 0.2 to 0.8%. 2. 2. These results indicate that the musculature in flexible part comprises a high proportion of collagen. 3. 3. The major collagen from the crustacean muscle was found to be similar to Type V collagen from the vertebrate muscle with respect to the solubility and amino acid composition. © 1989.