Abstract: Blast (http://www.ncbi.nlm.nih.gov/blast) searches was employed to obtain homologous porcine ESTs in the porcineEST databases with the mRNA sequence of human ubiquitin B (UbB) gene (GenBank accession No NM018955). And a 894 bp cDNA fragment (GenBank accession No. EF688558) was amplified and subsequently sequenced using total RNA of Landrace pig longissimus dorsi muscle as the template after in silico cloning. The cDNA fragment of porcine UbB gene contains a complete ORF encoding a deduced protein of 229 amino acid residue. The porcine UbB gene contained two exons and one intron spanning approximately 1.5 kb, and the exon/intron boundaries confirmed the GT-AG rule. Analysis of the porcine UbB gene genomic DNA sequences showed that it was highly homologous to that of other species such as Homo sapiens (92%), Pan troglodytes (91%), Mus musculus (91%), Rattus norvegicus (91%) and Gallus gallus (89%), and all these species shared the same amino acid sequence. Result of semiquantitative RT-PCR revealed that UbB gene was highly expressed in heart, liver, kidney and cerebellum, followed by spleen, lung, stomach, bladder, longissimus dorsi muscle, cerebrum, and the lowest in fat and hypothalamus. At the same time, we find that the UbB gene was differentially expressed between Lantang pig and Landrace pig in liver, spleen, lung, kidney, stomach, bladder and longissimus dorsi muscle.