Insulin-like growth factor 1 receptor (IGF-1R) is a main receptor of IGFs family which plays a critical role in the postnatal growth and skeletal growth in many species. However, there are few reports of IGF-1R gene structure and its effects on growth traits in SHEEP. The objectives of this study were detection of IGF-1R polymorphisms and assessment of their associations with growth traits in Iranian MAKOOEI SHEEP. Hence, 200 MAKOOEI lambs were genotyped through polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP). The studied traits were birth weight (BW), weaning weight (WW), 6 months weight (6MW), average daily gains from birth to 3 months (ADG0-3), from 3 months to 6 months (ADG3-6), from birth to 6 months (ADG0-6) and corresponding Kleiber ratios (KR0-3, KR3-6, KR0-6). For this genetic position, three types of banding patterns (AA, AB and BB) were identified with the frequencies of 0. 69, 0. 16 and 0. 15, respectively. In this study, IGF-1R genotypes indicated the significant associations with 6MW, ADG0-6, KR0-3 (P<0. 05) and ADG0-3 (P<0. 01). In all of the significant traits, The AA genotype was linked to the highest values, while the BB genotype was linked to the lowest values. The results of this study indicated that single nucleotide polymorphism (SNP) variation in IGF-1R gene can be used as a mo-lecular marker for improving of growth traits in marker assisted selection programs in SHEEP.