The aim was to estimate the genetic parameters for birth and weaning weights of Turkish Merino lambs by separating direct genetic, maternal genetic and maternal permanent environmental effects. Data and pedigree information of the Turkish Merino sheep used in this study were collected at the Marmara Animal Breeding Research Institute from 1995 to 2001. Variance components for birth and weaning weights were estimated by the REML technique. Six different animal models were fitted by including or excluding maternal effects. Depending on the model, h(d)(2) varied from 0.092 to 0.327 for birth weight and from 0.057 to 0.120 for weaning weight. Estimates of m(2) ranged from 0.101 to 0.271 for birth weight and from 0 to 0.083 for weaning weight. The maternal permanent environmental effect was significant for both traits. When fitted in models, estimates Of r(am) were high and negative for birth and weaning weights. In conclusion, maternal effects on birth and weaning weights of Turkish Merino lambs were significant and may be taken into consideration in any selection program on this breed.