Several recent studies have indicated that the paranasal sinus bones undergo pathophysiological changes in patients with chronic sinusitis. We examined the mineralization activity of osteoblasts and the production of osteocalcin and cytokines in cultured human osteoblasts derived from ethmoidal bones treated with vitamin D3, vitamin K2, and warfarin to investigate the metabolic effects of these treatments on paranasal sinus bones. In the bones treated with vitamin D3 plus vitamin K2, osteocalcin production and the ratio of the mineralization of osteoblasts were increased. Warfarin inhibited the promotive effects of vitamin K2 in the presence of vitamin D3. With regard to TGF-beta production, there was quite a difference in response depending on the isoforms. In conclusion, we have demonstrated that these vitamins and warfarin may be useful in improving bone metabolism in paranasal sinus bones, and may additionally improve the pathogenesis of chronic sinusitis.