In this study, determination of collagen in Kıvırcık and Dağlıç lamb skins and its influence on leather quality depending on race, age and sex were studied. The materials were skins of Dağlıç and Kıvırcık Breed for meat and which are native animals for Turkey, giving durable products valued in terms of end use. The aim was to determine earlist possible slaughter age for the best quality leather production according to the outcome. The lambs were chosen from Balikesir-Kepsut vicinity in the Western Anatolia region. Each breed had 12 males and 12 females slaughtered at the age of 3 and 6 months. Total 48 skins were processed. After the slaughter, the skins were tested for the determination of the amount of collagen after soaking, for the amount Of Chromium Oxide after neutralization and for the physical parameters after finishing. The physical parameters studied included the measurement of thickness, parallel and perpendicular elongations and respective tensile strengths, grain cracking, burst strength and tear strength. The results indicated that the amount of collagen increased with age in both sexes and the breeds and in turn, the best slaughter age was concluded to be the 6 months of age for both breeds valued on the finished products in terms of physical parameters, particularly with respect to tensile, tear and grain cracking strengths.