This study was undertaken to explain the diversity of casein alpha S1 (CSN 1S1) gene in ruminant animals. The neighbour joining tree inferred the genetic distances among and between species of the CSN1S1 sequences. The tree showed a closer genetic distance between the sequences of Capra hircus and Ovis aries, Bubalus bubalis and Bos taurus, Capra hircus and Bubalus bubalis as well as Bos taurus and Capra hircus. UPGMA tree derived from the consensus sequences, indicates that Bos taurus sequences were more closer to Bubalus bubalis sequences, compared to the sequence of Ovis aries and Capra hircus respectively. The results of the substitution pattern were more homogenous between the sequence of Capra hircus and Ovis aries (0.00) and Capra hircus and Bubalus bubalis (0.00) followed by the sequence of Bos taurus and Capra hircus (0.01) whereas the lowest homogeneity substitution pattern was observed between the sequence of Bos taurus and Bubalus bubalis (0.31). The highest evolutionary divergence was observed between the sequence of Ovis aries and Bubalus bubalis and the evolutionary divergence appeared to be species wise. The results indicates that all the CSN1S1 sequences of the selected ruminant species were not significant and the test implies that the strict-neutrality for synonymous (dN) and non-synonymous (dS) substitution from the sequences used were neutral. This findings would aid in understanding of species genetic variation and similarities resulting from their sequences.