Abstract: The inclusion of High Protein Distillers Dried Grains (HPDDG) in Juvenile rainbow trout (Oncorhynchus mykiss) diets was evaluated in a 73 day feeding trial. Three experimental diets contained 0, 10, 20% HPDDG, with the HPDDG, directly replacing fish meal as a protein source. With each incremental increase in HPDDG, there was a significant decrease in total and percent weight gain as well as an increase in feed conversion ratio, among the treatments. No significant differences in mortality, gut inflammation or any fish health measures were observed among the diets. The hepatosomatic index did not significantly change with changes in dietary HPDDG. Fillet crude protein levels were significantly lower in trout receiving the highest amount of dietary HPDDG. There were no differences in fillet lipid concentrations among any of the dietary treatments.