This experiment was conducted to measure the effects of fish meal and formaldehyde treated soybean meal (HCHO-soybean meal) on the protein and amino acid utilization and on the growth responses of growing Holstein bulls. The results obtained were as follows ; l. Dry matter digestibilities in dacron bag inserted into fistulated steer were the lowest in fish meal, followed by HCHO-soybean meal and soybean meal and nitrogen digestibility was the highest in soybean meal followed by fish meal and HCHO-soybean meal. Dry matter disappearance rates of fish meal, HCHO-soybean meal and soybean meal in the rumen were 11.53, 13.26 and 14.72%/h, and nitrogen disappearance rates were 11.54, 12.36 and 15.17%/h, respectively. 2. Nitrogen digestibilities of fish meal, HCHO-soybean meal and soybean meal were 37.1, 21.4 and 79.2% in the rumen and 52.0, 76.7 and 20.4% in the small intestine, respectively. Total amino acid disappearance of fish meal, HCHO-soybean meal and soybean meal were 36, 41, 60% in the rumen and 51, 55 and 37% in the small intestine, respectively. 3. Improvements of daily growth of growing Holstein bulls fed diets containing fish meal, HCHO-soybean meal and soybean meal were 16.2, 18.4 and 11.3%, respectively over diet containing urea (0.735kg gain/day) and improvements of feed conversion were 15.2, 16.2 and 15.2% as compared with urea diet. Daily weight gains of growing Holstein bulls were higher by 4.3 and 6.2% in diets containing fish meal and HCHO-soybean meal as compared with soybean meal diet, but there were no difference between HCHO-soybean meal and fish meal diets.