Objective: To explore a feasible method to detect tumor stem-like cells in human lung adenocarcinoma cells(LAC),and to analyze the properties of the sorted side population(SP)cells. Methods:Fluorescence-activated cell sorting assay(FACS)was performed to sort the SP and non-SP cells of LAC. MTT,colony formation and in vivo tumorigenesis assays were performed to analyze the proliferation capacity of SP and non-SP cells in vitro and in vivo. Flow cytometric assay was performed to detect the cell cycle and differentiation of SP cells. RT-PCR assay was performed to detect the expression of ATP-binding cassette transporter G2(ABCG2) mRNA in SP and non-SP cells. Results:Results from FACS showed that SP cells were detected in approximately 1.88% of LAC. MTT and in vitro colony formation assays showed that the in vitro proliferation capacity of SP cells was significantly stronger than that of non-SP cells. Additionally,the in vivo tumorigenesis capacity of SP cells was significantly stronger than that of non-SP cells. Cell cycle analysis indicated that the cell number of G0/G1 phase in SP cells was higher than that in non-SP cells(P < 0.05). The rates of SP cells in SP and non-SP populations were approximately (1.46±0.08)% and (0.12±0.04)%,respectively. Moreover,the level of ABCG2 mRNA in SP cells was 3.3 times of that in non-SP cells(P < 0.05). Conclusion:The SP cells sorted from LAC possessed characteristics of cancer stem-like cells,and SP cells sorted by FACS could be an effective method used to sort lung cancer stem cells.