Galvanic　coupling　intra-body　communication　is　a　low　power　consumption　method,　which　is　especially　suitable　for　the　Body　Area　Network　(BAN)　in　medical　or　healthcare　domain.　Based　on　the　physical　layer　modeling　to　get　an　insight　in　the　propagation　mechanism　in　the　human　body,　it　is　necessary　to　analyze　the　MAC　layer　performance　for　the　galvanic　coupling　IBC.　A　multi-node　physiological　signal　monitoring　and　transmission　system　was　assumed　as　the　application　scenario　in　this　paper.　Two　common　protocols,　namely　TDMA　and　CSMA/CA　were　selected　to　calculate　and　compare　the　energy　consumption　per　bit　in　wireless　networks　consisting　of　intra-body　communication　and　ZigBee　nodes.　The　results　showed　that,　due　to　the　low　power　consumption　during　the　transmitting　and　receiving　period,　the　TDMA　protocol　in　an　IBC　network　had　the　lowest　energy　consumption　of　around　1.3　mu　J/bit,　which　was　also　nearly　constant　with　the　number　of　nodes.　The　energy　consumption　of　CSMA/CA　protocol　in　an　IBC　network　increased　slowly　along　with　the　number　of　nodes,　and　was　a　little　lower　than　the　consumption　of　a　TDMA　protocol　in　a　ZigBee　network,　because　of　the　higher　data　rate　of　ZigBee.　A　large　amount　of　energy　was　consumed　in　channel　listening　to　avoid　data　packet　collision.　So　the　CSMA/CA　protocol　in　a　ZigBee　network　used　the　highest　amount　of　energy　per　bit.