When frozen fish muscle was ground, there were drastic changes in salt-soluble protein, viscosity, emulsifying capacity, and elasticity compared to samples from fish thawed prior to grinding. When cod muscle was tested for cooked texture in sausages, ground-while-frozen muscle was unacceptably soft and crumbly while the ground-while-thawed muscle was acceptable. Electron microscopy showed the sarcomeres of pollock muscle ground while frozen or thawed to be similarly disrupted. It appears that differences in functionality losses of pollock, and presumably of other species, were related to the particular type of fragmentation of muscle tissue that occurred when fish was ground-while-frozen rather than to the disruption of the submicroscopic structure of muscle.