The aim of this study was to investigate the effects of metabolic syndrome (MetS) on bone mineral density (BMD) and microstructure of jawbones, and circulating bone metabolic markers. MetS was induced in male Wistar rats by a 16-week high-sucrose drinking water diet. Mandibles were analyzed for BMD and microstructure by standard radiographs and X-ray diffraction. BMD of three different regions of mandible in MetS group was significantly lower compared to control group. The diffraction intensity of mandibular bone in MetS group was significantly decreased (8.2%) compared to control group; however, crystallite radiuses of mandibular bone samples in both groups were not significantly different. In MetS group, serum bone-specific tartrate-resistant acid phosphatase-5b (TRACP-5b) activity was significantly increased (47%), whereas bone-specific alkaline phosphatase (BALP) activity was significantly decreased (44%) compared to control group. The serum magnesium level in MetS rats (1.82 +/- 0.27 mg dL(-1)) was lower than that of controls (2.11 +/- 0.16 mg dL(-1)). Rats with MetS had significantly higher serum calcium level (9.70 +/- 0.41 mg dL(-1)) than the controls (9.21 +/- 0.50 mg dL(-1)). Overall data suggested that MetS is associated with a significant decrease in BMD and slight deterioration in microcrystallite structure of the jawbones. The changes in TRACP-5b and BALP activities and serum Ca2+ and Mg2+ concentrations also support these findings at a biochemical level.