Objective To determine the synergic effect of simultaneously blocking epidermal growth factor receptor (EGFR) and cyclooxygenase-2 on the growth inhibition of human lung cancer A549 cells. Methods The A549 cells were treated by gefitinib (5 μmol/L), celecoxib (25 μmol/L), or a combination of them at the same dosages respectively for 48 h, and the cells without treatment served as control. Cell growth was detected by trypan-blue exclusion assay, apoptosis rate and cell cycle were measured by flow cytometry and Hoechst33258 staining, expression of EGFR and COX-2 proteins was determined by Western blotting. Results With time and dose increase, both gefitinib and celecoxib showed stronger inhibitory effect on the growth of A549 cells, and the combination of them had more significant inhibitory effect than the gefitinib and celecoxib groups (P<0.01). The combination group also had obvious higher apoptosis rate than the monotherapy groups (32.40% vs 7.12% and 8.43%, P<0.01). The proportion of the cells at S stage was (3.2±0.9)% in the combination group, significantly decreased when compared with those in the gefitinib and celecoxib groups [(37.4±1.6)%, (21.0±3.1)%, P<0.01]. The combination group had obviously more cells arrested at G₀/G₁ stage than the monotherapy groups [(87.2±6.4)% vs (61.4±5.2)% and (51.8±4.7)%, P<0.01]. The protein levels of EGFR and COX-2 were significantly lower in the combination group than the other 2 groups (P<0.05). ConclusionThe combination treatment of gefitinib and celecoxib exerts inhibitory effect through blocking both EGFR- and COX-2-related pathways, and the regimen might provide a promising strategy for cancer therapy and chemoprevention in lung cancer.