Leptin is produced by adipocytes and plays a critical role in the regulation of bodyweight through reducing food intake and stimulating energy expenditure. Leptin gene can participate in many physiological functions and regulation of food intake. In order to identify the polymorphism in a region of the second intron of the leptin gene, blood samples were taken randomly from 150 Raeini cashmere goats. Genomic DNA was extracted and a fragment with a length of 442 bp was amplified from the second intron of leptin gene using PCR-RFLP method. The statistical analysis identified three band patterns of AA, AB and BB with frequencies of 57.0, 3.0 and 13.0, respectively. The A and B alleles showed frequency of 72.0 and 28.0, respectively. Shannon index and effective number of alleles for the leptin gene were 5898/0 and 6673/1 respectively. Analysis of the body size related traits with leptin genotypes showed that while birth weight was not associated with this gene weaning weight, body length, body height and chest circumference were significantly associated with identified polymorphisms in this gene (P<0.05).