This study was carried out to evaluate lamb weights and daily weight gains and to estimate genetic and phenotypic parameters to develop breeding strategies over the genetic improvement of growth traits in Stonmez lambs. Genetic and non-genetic parameters on growth traits of 574 Sonmez lambs sired by 12 rams over the years 2001-2004 were evaluated. Sex of lamb, birth type and year, age of dam and ewe weight were significant sources of variation for lamb body weight and gains. Estimates of heritability for birth weight, 2-months weight, pre-weaning, 4 months weight and post-weaning daily gains were 0.25, 0.36, 0.61, 0.50 and 0.61, respectively. Genetic and phenotypic correlations among growth traits were found significant. These findings show that there is an opportunity to improve Sonmez lambs based on the selection for the growth rate.