Alantolactone (ALA), a sesquiterpene lactone compound obtained from Inula helenium root, is known to have anticancer activity in many types of cancer. Paclitaxel (PAX) is an effective first-line chemotherapeutic drug and is widely used in the treatment of lung cancer. The in vitro anticancer efficacy of combined treatment of ALA with PAX was investigated in the A549 human lung cancer cell line. The results show that ALA potentiated the effect of PAX-induced growth restriction and apoptosis in A549 cells. The combined administration more effectively decreased the Bcl-2 expression and increased Bax gene expression in cells compared to ALA or PAX alone. Also, co-treatment of ALA and PAX caused apoptotic nuclear formations. Additionally, coadministration increased the caspase-3 and caspase-9 levels more than PAX or ALA alone. The increase in NF-κB gene expression levels suggests that an NF-κB-independent apoptotic trigger mechanism operates in cells. Together, the present in vitro findings suggest that ALA may contribute as a potential therapeutic strategy in the treatment of lung cancer.