Objective: To investigate whether the side population cells (SP cells) exist in human gallbladder carcinoma cell line and the differences of drug resistance gene ABCG2 expression in SP cells, non-SP cells and GBC-SD cell lines. Methods:Fluorescence activated cell sorter (FACS) was used to sort the SP and non-SP cells from GBC-SD cell line of gallbladder carcinoma of human being. Then, the sorting cells were cultured and detected the expression of ABCG2 gene among the SP cells, non-SP cells and GBC-SD cell lines by using reverse transcription polymerase chain reaction (RT-PCR), immunofluorescence chemistry, weste blot and flow cytometry techniques. Results:A very small fraction cells (0.64 ± 0.08%) were isolated through FACS analysis which had the potency of stem cells and highly expressed ABCG2 gene (89.56 ± 3.86%). On the contrary, there were nearly no expression in non-SP cells (1.32 ± 0.49%) and lower expression in GBC-SD cell line (12.37 ±1.61%). Conclusion: The side population cells that had the potency of stem ceils existed in human gallbladder carcinoma cell line and over-expressed the drug resistance gene ABCG2. They may be play an important role in drug resistance of tumor.