RELA gene is a pleiotropic transcription that is present in almost all living cells where several signal transduction events end points were initiated by many arrays of stimuli that were related to many biological processes such as inflammation, immunity, differentiation, cell growth, tumorigenesis and apoptosis in the cells. The nucleotide and amino acid sequence (AAS) of RELA gene of pig and other mammalian species were downloaded from the National Center for Biotechnology information (NCBI) data base, United State of America and Universal protein resources (Uniprot) database, United Kingdom. Data generated were analyzed by bioinformatics tools. The results showed a high variation of AAS among the mammals where only four mammals have the same AAS length (551) with pig while others were not. The RELA gene of pig shared very high percent identity with all mammals ranging from 95.5% (warthog) to 83.5% (guinea pig) and similarity percentage ranged from 85.1 to 99.5% where the warthog had the highest percentage value while the least mammal was Guinea pig. The tree showed RELA gene with two clades; the first for mammals and the second for non-mammals. The RELA gene of pig was in the same cluster with the other Suidae family, warthog and babirusa. For the protein structure obtained, only 43% can be meaningfully predicted from the 61% residues modelled at more than 90%. The domain architecture of RELA protein structure contained mainly RNA Recognition motif and region of low complexity. The domainstarting position of all the organisms ranged from 191 to 210 while the termination of all the mammals ranged from 102 to 306 amino acids.The region of low complexity starting point ranged from position 173 to 462while termination positions ranged from 184 to 474. The evolution relationship of RELA gene of pig and other mammalian species were highly related and conserved among the mammalian species; they have high comparability and they evolved from common ancestors.