Distillers dried grains with soluble (DDGS) is a co-product from ethanol industry. Corn DDGS is low in lysine and contains moderate crude protein concentrations (28 to 32%) and relatively high fiber, thus limiting the inclusion level of DDGS in practical fish feed. However, through applying advanced processing techniques, the nutritional quality of corn DDGS can be modified, and recently Marquis Grain Inc. developed a high protein (48%) DDGS product. Until now , this new DDGS product had not been tested as a protein substitute in practical diets for Atlantic salmon (Salmo salar). Therefore, a 12-week feeding trial was conducted to evaluate this high protein DDGS as a soybean meal (SBM) replacer for Atlantic Salmon diets and determine growth, nutrient digestibility, intestinal morphology, and health performance. A low fish meal (15%) based control diet (Diet-1, Control) was produced, then 25%, 50%, 75% and 100% of SBM protein from the control diet were replaced with DDGS protein for diet groups Diet-2, Diet-3, Diet-4 and Diet-5, respectively. All experimental diets were fed to satiation, twice daily to triplicate groups of Atlantic salmon juveniles (initial weight 21g). Following the 12-week growth trial, in vivo digestibilities of the five diets were also determined . After the feeding trial, final weight, specific growth rate, weight gain and feed utilization were not significantly different among the treatment groups. Significantly higher and lower whole body moisture content was observed in fish feed diet group Diet-3 and Diet-4, respectively; other groups showed intermediate values. In comparison to the control diet, increased final whole body protein content was observed when DDGS was included and was significantly higher in Diet- 3. Except for cystine, lysine, tryptophan, tyrosine, proline and taurine, all other measured amino acids were significantly influenced by dietary treatments. H igher and lower values were observed in fish fed Diet-3 and Diet-5, respectively; other dietary groups showed intermediate values. DDGS inclusion significantly increased dietary lipid digestibility, with fish fed Diet-4 and Diet-5 having higher values, followed by Diet-3. Diet-2 resulted in intermediate value s, with significantly lower values observed in fish fed the control diet . In terms of immune response and oxidative stress, DDGS inclusion increased indices for nonspecific immune response and oxidative stress tolerance. Based on the overall findings, we can conclude that the high protein DDGS tested can be effectively used as a SBM replacer in Atlantic Salmon diets.