Objective To explore the role of sphingosine kinase 2 (SphK2) in 5-fluorouracil (5-FU)-induced apoptosis in human colon cancer HCT116 cells. Methods Hoechst33342 staining was used to examine the apoptosis morphological changes of HCT116 cells 48 h after treatment with 5-FU; flow cytometry was used to detect the apoptotic ratio of HCT116 cells and the effects of SphK2 (down-regulation and over-expression) on 5-FU-induced apoptosis were analyzed. Western blotting analysis was used to examine the changes in the activated forms of SphK2 and apoptotic marker protein in HCT116 cells after exposure to 5-FU. Results 5-FU induced significant apoptosis in HCT116 cells as reflected by apoptosis characteristics-condensation and fragmentation of chromatin. Interference of SphK2 significantly increased 5-FU-induced apoptosis in HCT116 cells compared with non-interfered group (P<0.01), accompanied by increased apoptotic marker protein. On the contrary, the apoptosis ratio of the cells with SphK2 over-expression was significantly decreased compared with vehicle plasmid-transfected group (P<0.01), accompanied by decreased apoptotic marker protein. Moreover, 5-FU greatly increased activated SphK2. Conclusion SphK2 negatively regulates 5-FU-induced apoptosis in HCT116 cells.