1. The stability of hemoglobin of rainbow trout under frozen conditions in oxyform, carboxyform, and cyanometform was examined.
2. Carboxyhemoglobin retained its original electrophoretic banding pattern after 14 days of frozen storage, whereas oxyform and cyanometform hemoglobins did not.
3. Banding patterns changed in some samples in all treatment groups after 21 days of storage.