1. The nutritive and biological values of the dry heat-treated beef protein were estimated by the growth and the nitrogen balance methods, using weaning and young rats respectively.2. At a 10 per.cent level of protein intake in the diet, the digestibility and biological values of the beef protein dried at two different temperatures were respectively as follows: at 60℃, 94.1 and 85.5; at 140℃, 88.3 and 76.1.3. The protein efficiency of beef dried at 60℃, 80℃, 100℃ and 140℃ obtained at a 10 per cent level of protein intake during a period of 4 weeks were as follows: 60℃, 2.70 + 0.09 g; 80℃, 1.79?0.12g; 100℃, 1.78?0.13 g; and 140℃, 1.33?0.35g.4. The higher the temperature, the lower the nutritive and biological values of dried beef protein. This decrease appears to be the result of lowered digestibility of the dried beef protein due to a change in the peptide linkages which renders them less susceptible to enzymatic hydrolysis.