Abstract: Objective To clone and analyze the full-length cDNA sequence of guinea pigs bile salt export pump gene(BSEP) and detect its expressions in cholelithiasis guinea pigs liver. Methods The BSEP gene full-length cDNA of guinea pigs was amplified by 3'and 5'RACE.Bioinformatic methods were applied to analyz and identify the sequence. Real-time PCR was used to quantification BSEP gene expressions in Cholelithiasis guinea pig liver.Results The length of the guinea pigs BSEP gene cDNA was 5579 bp, containing altogether 28 extrons and a 3963 bp-length open reading frame(ORF) encoding a 1320- amino -acids protein. BSEP mRNA expressions in cholelithiasis guinea pigs liver were significantly decreasses compared to the normal group（P<0.01）. Conclusions Down-regulation of BSEP mRNA expressions in cholelithiasis guinea pigs liver may be relative to the formation of cholelithiasis.

Key words: bile salt export pump (BSEP), gall-stone, guinea pig, gene clone, bioinformatics