BACKGROUND: Anaplastic thyroid cancer (ATC) is one of the most aggressive malignancies in humans, and its progression is poorly controlled by existing therapeutic methods. Curcumin has been shown to suppress inflammation and angiogenesis. In this study, we evaluated whether curcumin could augment docetaxel-induced apoptosis of ATC cells. We also analyzed changes in nuclear factor kappaB (NF-kappaB) and cyclooxygenase-2 (COX-2) expression levels to delineate possible mechanisms of their combined action. METHODS: ATC cells were cultured and treated with curcumin and docetaxel alone or in combination. The effects on cell viability were determined by MTS assay. Apoptosis was assessed by annexin V staining and confirmed by flow cytometric analysis. Caspase, COX-2, NF-kappaB levels were assayed by Western blotting. RESULTS: Curcumin combined with docetaxel led to lower cell viability than treatment with docetaxel or curcumin alone. Annexin V staining followed by flow cytometric analysis demonstrated that curcumin treatment enhanced the docetaxel-induced apoptosis of ATC cells. Additionally, curcumin inhibited docetaxel-induced p65 activation and COX-2 expression. CONCLUSION: We conclude that curcumin may enhance docetaxel's antitumor activity in ATC cells by interfering with NF-kappaB and COX-2. Our results suggest that curcumin may emerge as an attractive therapeutic candidate to enhance the antitumor activity of taxanes in ATC treatment.