Feeding a dog of a large breed with a diet exceeding the National Research Council (1974) recommendations for energy, protein, calcium, phosphorus and vitamin D may result in disturbances of skeletal development. The effects of excess energy and various calcium:phosphorous ratios per se have been reported by others. The role of dietary protein, especially with regard to calcium metabolism and skeletal development, in large breed-dogs is reported in this article. Seventeen Great Dane pups, 7 wk of age, were divided into three groups. During 18 wk each group received isoenergetic dry food (approximately 15 kJ metabolizable energy/g) containing 31.6, 23.1 or 14.6% protein on dry matter basis. No differences were found among the high (H-Pr), normal (N-Pr) and low protein (L-Pr) groups for the height at the shoulder. Significant differences were found between the H-Pr and L-Pr groups for body weight and plasma albumin and among all three groups for plasma urea. The differences in protein intake per se had no demonstrable consequences for calcium metabolism and skeletal development. A causative role for dietary protein in the development of osteochondrosis in dogs is unlikely.