Leptin is a 16-kDa polypeptide hormone synthesized and secreted predominantly by Adipose tissue. It functions regulating body weight, food Intake, energy expenditure, reproduction and immune system functions. The gene encoding Leptin was mapped to Bovine chromosom 4 and it consists 3 exons and 2 introns of which only two exons are translated into protein. It is considered as a candidate gene for milk performance related traits in cattle. In this study, we use PCR_RFLP technique to screen for A59V polymorphism is situated in exon 3 of leptin gene in 252 cattle belonging to 4 herds. Digestion a 331 bp fragment of PCR product with HphI revealed two alleles: allele A had a one fragment 331 bp (not digested) and allele B had 2 fragments 311 and 20 bp. Genotype frequencies in all herd were 0.588, 0.388 and 0.024 for AA, AB and BB respectively and gene frequencies were 0.782 and 0.218 for allele A and B, respectively. We investigated effect of A59V polymorphism in the leptin gene on production trats and some reproduction trats. significances of the genotype effects were estimated using approximated F - statistic provided by SA ( v.8 , GLM procedure ). this study show that genotype effected on length of pregnancy (p 0.01) and tended to be significant for fat percent (0.05 lt;0.1). animals homozygos for A allele had higher length of pregnancy and animals with the AB genotype produced lower fat percent.