Growth performances of 202 Kivircik (K) and Karacabey Merino (KM) lambs reared under semi-intensive management in Turkey were evaluated. The aim of this study was to compare the performance of K and KM lambs in terms of weights at birth and at 30-day intervals from birth to 150 days of age and of average daily gain between these intervals. Data were collected in 2005, and analyzed by GLM procedures of SAS. The effects of genotype, type of birth, sex of lamb, linear regression of lambs' age, and dam Postpartum body weights were significant. Sex variation became unimportant as lambs grew older. Male lambs were heavier than females at birth and at all ages. Lambs born to older dams were heavier than those born to younger dams at all ages. Average daily weight gains during the growth period were significantly affected by genotype, sex, type of birth and age of dam. (C) 2009 Elsevier B.V. All rights reserved.