The objectives of this work were to compare ice crystal sizes of pre-rigor Atlantic salmon fillets subjected to two processes of superchilling and to assess the size changes during storage of the superchilled samples at -1.7 ± 0.3 C. The fillets were superchilled by an impingement freezer at either a slow rate (-20°C, 153 W/m2.K, 4.2 min) which is referred to as process S or a fast rate (-30°C, 227 W/m2.K, 2.1 min) which is referred to as process F before storage for 29 days. Significantly smaller (p<0.05) equivalent diameters of ice crystal occurred at faster superchilling rate when compared to slower superchilling rate. The influence of these processes on the microstructure of pre rigor salmon fillets was studied. The equivalent diameter of the intracellular ice crystals formed were 60 ± 5 and 23 ± 1 μm for the samples subjected to processes S and F, respectively. Significant differences were observed between the size of ice crystals formed during the superchilling process and superchilled storage. The formation of ice crystals within salmon muscle regardless of the superchilling rates was an important factor in reducing cell structure damage. Copyright © 2012 Published by Elsevier Ltd.