In order to investigate energy utilization of defatted rice bran and Comfrey (Symphytum Paregrinum) meal, hatched single comb White Leghorn male chicks were fed for 10 days on a commercial chick mash and for the subsequent 10 days on diets containing 17.0 % of cellulose, wheat bran, defatted rice bran and Comfrey meal, respectively. During experimental feeding period, daily body weight gain did not show significant differences among treatments though birds fed defatted rice bran diet consumed more diet than those fed Comfrey diet. And protein retention did not show significant differences while buds fed Comfrey diet retained lower lipids than those fed other diets. Ratio of metabolizable energy to gross energy(MEn/GE) of cellulose diet was lower than those of defatted rice bran and wheat bran diets. And the ratio of productive energy to MEn(PE/MEn) was not affected by the experimental diets though increasing tendency in wheat bran diet and decreasing tendency in defatted rice bran diet were found. MEn of wheat bran, defatted rice bran and Comfrey meal were 43.2, 34.2 and 9..0 % of GE, respectively, and contained 0.594, 0.018 and -0.023 ㎉ of PE per gram dry matter, respectively. Thus defatted rice bran and Comfrey meal were not utilized for productive energy. MEn intake and heat production per metabolic body size(㎏^(0.75)) was higher in birds fed defatted rice bran diet and lower in birds fed Comfrey diet compared with those of cellulose or wheat bran diets. The results indicated that unknown substances might be contained in defatted rice bran to increase heat production and in Comfrey meal to decrease feed intake.