Abstract: A feeding trial was conducted in various levels of corn distillers dried grains with solubles (DDGS) were fed in broiler diets formulated to be either isocaloric using metabolizable energy levels similar to current U.S. poultry industry levels or formulated to contain optimum density commensurate with 1% supplemental poultry oil. In each diet type, levels of 0, 15 and 30% DDGS were incorporated. This resulted in six dietary treatments with four pens of 25 males per treatment. Diets were developed for starter (0-14 d), grower (15-28 days) and finisher periods (29-42 days) and were formulated to meet digestible amino acid specifications of a major poultry breeder, adjusted to the energy content of the diet. Bulk density and pellet quality of mixed feeds were determined. At the end of the study, five representative birds per pen were processed for dressing percentage and parts yield determination. Pellet quality decreased with increasing level of DDGS used. There was little difference in pellet quality between diets with 0 or 15% DDGS but quality deteriorated severely in diets with 30% DDGS. Diets formulated to optimum energy had better pellet quality due to lower supplemental poultry oil. Over the 42 days study, birds fed diets with 30% DDGS had significantly lower body weight and significantly higher feed conversion than did birds fed the control diet with no DDGS. Birds fed diets with 15% DDGS did not differ significantly in 42 days BW or feed conversion from birds fed the control diet with no DDGS nor with the birds fed diets with 30% DDGS. It appeared that a portion of the reduced performance associated with the higher level of DDGS might have been associated with the reduced pellet quality and the bulk density of the diet, rather than any nutritional deficiency. Therefore, approaches to feed manufacturing that enhance pellet quality may enhance usage of higher levels of DDGS in broiler diets.