Macrophages in tumor are mostly M2-polarized and have been reported to promote tumorigenesis, which are also defined as tumor-associated macrophages (TAMs). beta-elemene has therapeutic effects against several cancers, however, it remains unknown whether beta-elemene could inhibit cancer by targeting TAMs. Herein, we examined the effect of beta-elemene on macrophages to elucidate a novel mechanism of beta-elemene in tumor therapy. We showed that the conditioned medium of M2 macrophages promoted lung cancer cells to migration, invasion and epithelial mesenchymal transition, which could be inhibited by beta-elemene. Moreover, beta-elemene regulated the polarization of macrophages from M2 to Ml. beta-elemene also inhibited the proliferation, migration, invasion of lung cancer cells and enhanced its radiosensitivity. These results indicate beta-elemene suppresses lung cancer by regulating both macrophages and lung cancer cells, it is a promising drug for combination with chemotherapy or radiotherapy. (C) 2017 Elsevier Inc. All rights reserved.