This study was conducted to investigate the multiple aspects of mutant fertile gene and their effects in reproductive performance of Iraqi Awassi ewes. A total of 82 Iraqi Awassi (2-3 years) old with an average live body weight 45 kg were obtained from two locations (First , College of Agriculture , second , Agricultural Research Station / Ministry of Agriculture) in Abu-Ghraib , (30 km) south – west of Baghdad, were used in this study from August 2009 to August 2010. Investigation was carried out for multiple fertility gene (FecB) using the (PCR-RFLP) technique. Blood samples (5 ml/ewe) were drawn from the juglar vein using vacutainer tubes with anticoagulant material (ACD). Genomic DNA was extracted from whole blood for each sample using (Wizard genomic DNA purification Kit). The concentration and the purity of extracted DNA were measured with Spectrophotometry. Gel concentration (0.8%) was used for the purpose of electrophoresis. Specific parts of mutant region were isolated and amplified using (polymerase chain reaction) and specific (DNA markers) technique. For the purpose of natural point mutation diagnosis in the resulting PCR product is through the digestion of (FecB) gene (190 bp), by using restriction enzymes (Ava II). The results of the study showed that: Awassi ewes studied with (++) genotype revealed the absence of fertility genes (FecB). Twining percentage found in some Awassi ewes were not related to this gene and may be are related to other fertility genes or to other factors such as nutrition. No significant differences were observed in the birth weight or body weight at 90 days postpartum.