The purpose of the present study was to determine the live weight development phases from hatchling to adolescent bird of Japanese quails bred in Kyrgyzstan, and to determine the age-related changes in body measurements. Adolescent birds were found to have a body length (distance between fi rst vertebra thoracalis to end of sacrum) coeffi cient of 3.0, a sternum front to rear end length coefficient of 3.3, a tibia length of 2.34, and a pelvic width (distance between right and left acetabulum) coeffi cient of 1.58. This indicates good development of the quails’ pectoral muscles and relative underdevelopment of their leg muscles. The main development phases were found to be between day 1 and 14 and again between day 35 and 42. During these phases, Japanese quails are very sensitive to external influences and require particular attention in their care. Based on findings and variation coefficients it was established that development is lowest during the first 7 days (10.21%-8.78%) and highest after day 7 up to day 49 (10.47%-25.06%) with growth returning to lower rates in the following phase. Quail chicks reach adolescence aft er 45 to 56 days with their body weight attaining 75% of the weight of full grown birds. This study was carried out in 2008 in the laboratory of the Department of Anatomy and Physiology of the Veterinary Faculty of the State University of Kyrgyzstan.