BACKGROUND: Studies have shown that cyclooxygenase-2 is associated with proliferation and apoptosis of glioma cells. OBJECTIVE: To investigate the effects of selective cyclooxygenase-2 inhibitor celecoxib on proliferation and apoptosis of C6 glioma cells in vitro. DESIGN, TIME AND SETTING: A cellular, molecular, controlled study was performed at the Central Laboratory and Room of Electron Microscope, Medical School, Xi’an Jiaotong University, China from March 2007 to March 2008. MATERIALS: C6 glioma cells during in vitro log phase were assigned to control and experimental groups. Celecoxib (Pfizer, USA), dimethyl sulfoxide (Sigma, USA), and MTT (Sigma, USA) were used for this study. METHODS: The control group was subdivided into blank control and dimethyl sulfoxide control groups. C6 glioma cells in the blank control and dimethyl sulfoxide control groups were incubated in Dulbecco’s modified Eagle’s medium supplemented with 10% calf serum and 0.3% dimethyl sulfoxide respectively. C6 glioma cells in the experimental group were separately treated with 60, 80, and 100 μmol/L celecoxib. MAIN OUTCOME MEASURES: Activity of C6 glioma cells was examined by MTT assay. C6 glioma cell cycle and apoptosis were determined by annexin V-fluorescein isothiocyanate/propidium iodide double-staining, followed by flow cytometry. Morphology and ultrastructure of C6 glioma cells were observed with an inverted microscope and a transmission electron microscope, respectively. RESULTS: Compared with the blank control group, cell density was reduced, adherence ability weakened, and irregular nuclei were visible, with the presence of chromatin condensation, margination, and some apoptotic bodies in the experimental group. Activity of C6 glioma cells was significantly decreased (P < 0.05), cell number was reduced during S phase, cell number was significantly increased during G_2/M phase (P < 0.01), and the apoptotic rate was significantly increased (P < 0.05) in the experimental group. These results were displayed in a dose- and time-dependent fashion. The outcomes were obvious in the 100 μmol/L celecoxib group following 72 hours of treatment. CONCLUSION: Celecoxib blocked proliferation and induced apoptosis of C6 glioma cells in a dose- and time-dependent fashion.