L ivestock production plays a major role in the life of farmers in developing countries. It enjoys a relative advantage of easy management, higher turnover, quick returns to capital investment and a wide acceptable of its products for human consumption when compared with other commercial livestock industry (Haruna and Hamidu, 2004). Among them, poultry industry provides high quality food for human consumption. Broiler production is becoming an important aspect of poultry production in many developing countries including Myanmar. However, the recent increase in the prices of conventional feed ingredients is a major factor affecting net return research Article Abstract | This experiment was conducted to evaluate the effects of dietary supplementation of rice distiller dry grains (rDDG) on growth performance and digestibility of broiler chicken. The 140 day-old broiler chicks were randomly allocated to five groups with four replicates. During starter period (1-21 day), commercial starter diet was fed to the experimental animals. During grower period (21-42 days), the experimental grower diets were isonitrogenously and isocallorically formulated with different levels of rDDG. They were T1 (without rDDG), T2 (5% rDDG), T3 (10% rDDG), T4 (15% rDDG) and T5 (20% rDDG). The cumulative feed intake, weight gain, feed conversion ratio and production efficiency index were measured. As cumulative feed intake, cumulative weight gain and feed conversion ratio (FCR), there were no significantly differences (p>0.05) among the broiler chicken fed dietary treatments (T1, T2, T3, T4 and T5) thorough out grower period (21-28, 21-35 and 21-42 days old age of broiler chicken) although the diet T5 containing 20% level of rDDG gave the tendency of lower in feed intake, greater in weight gain and better FCR as compared to other dietary treatments. The growth performance data throughout the experimental period (1-42 days) showed similar pattern as that of grower period. At the aspect of feed cost, feed cost per kg of feed was decreased as the inclusion levels of rDDG were increased in diets. However, the lowest feed cost per kg (p<0.05) of live weight was observed in broiler chicken fed the diet T5. There were no statistically differences (p>0.05) among the T1, T2, T3 and T5 diets in feed cost per kg of live weight. Regarding data for digestion trial, the dry matter intake, the organic matter intake, dry matter digestibility and OM digestibility of broiler chicken fed all dietary treatments were not significantly different (p>0.05). Thus, inclusion of up to 20% rDDG in grower diet have no detrimental effect on the growth performances of broiler chicken during grower stage (21-42 days of age) and it could be supplemented in grower broiler diets with least cost of feed (MMK per kg of feed and MMK per kg of live weight).