The aim of this study was to identify luteinizing hormone receptor (lhr) genetic polymorphism by using PCR-RFLP and detection of LH level in serum, also to investigate their possible association with ovarian inactivity and silent heat in Egyptian buffaloes. Blood samples were collected with and without EDTA from female Egyptian buffaloes raised in small holder under the same managemental conditions. The present study was conductedon90 Egyptian river buffaloes from different locations in Menoufia governorate which were divided into three equal (n=30) groups according to their reproductive history and ultrasonographic examination (ovarian inactivity, silent heat and control). PCR amplification of DNA samples were revealed 303 bp product using specific primers and digested with HhaI restriction enzyme. The results were revealed that all animals were a monomorphic pattern at 303 bp and genotyped as TT, which indicates the fixation of T allele and absence of C allele, except one silent heat animal was showed heterozygous genotype CT 155, 148 bp (overlapped bands). While, the average of serum LH concentration was significantly higher (P<0.05) in silent heat (2.17 mIU/ml) and control groups (2.2mIU/ml) than ovarian inactivity group (1.99mIU/ml). In conclusion, no genetic polymorphism was detected for lhr gene of the three groups but, average LH concentration in serum was showed a significant difference within ovarian inactivity group.