Butein is a flavonoid isolated from the bark of Rhus verniciflua Stokes and the flowers of Butea monosperma, and is known to be a potential therapeutic drug for treating inflammation and cancer. Cyclooxygenase (COX) converts arachidonic acid to prostanoids, and increased expression of its isoform, COX‑2, has been observed in lung cancer tissue. The aim of the present study was to investigate expression alteration of COX‑2 in A549 lung cancer cells following butein treatment at the mRNA and protein levels by quantitative polymerase chain reaction and western blotting, respectively. It was observed that COX‑2 mRNA and protein levels were significantly downregulated in the butein treatment group in comparison with the control group (P<0.05). In addition, the effects of butein on proliferation and apoptosis were evaluated. The data demonstrated that butein induces cell‑cycle arrest and apoptosis in human lung cancer cells. These results indicated that butein may be a promising candidate drug for lung cancer treatment.