Abstract: The aim of this study was to compare birth weights of Norduz and Karakas genotypes and determine the effects of gender, birth type, dam age and genotype on birth weight. The data were composed of a total of 204 (103 Norduz and 101 Karakas) lambs born in 2003 in Van, in located region of the Eastern Anatolia, Turkey. The effects of gender (p<0.05), birth type (p<0.05) and dam age (p<0.05) on birth weight were found to be significant, whereas difference among averages of birth weight of breeds was found to be non- significant. As a result, using of birth weight as crucial criterion for early selecting animal is based on determination and elimination of some factors affecting the trait.