The cDNA sequence of leuteinizing hormone (LH) beta subunit was determined to understand the molecular basis for silent oestrus behavior and poor response to superovulation in buffalo. The LH-β cDNA contains an open reading frame 426 bp long. The deduced sequence of the LH-β is 141 amino acids in length. The amino acid sequences of the Indian river buffalo LH-β subunit showed overall similarity to those of other mammals. The nucleotide sequence variability of LH-β was studied in more than ∼350 Indian buffaloes covering five different breeds. The results of the sequence analysis showed that the buffalo LH-β gene is not highly conserved and non-synonymous mutations are not rare, at least in the samples collected randomly from five different breeds and buffalo populations. A total of seven different variants were obtained. In spite of its crucial role in reproduction, variation of the LH-β gene was found present in this species. The polymorphisms found were unique in the Indian river buffalo population.