The metabolic syndrome is featured by the combination of obesity, dyslipidemia, hyperglycemia, and hypertension. It is well documented that obesity is positively linked to increased bone mineral density (BMD) and reduced fracture risk through body weight increase. Hyper-triglycemia and hypo-HDL-cholesterolemia, which are frequently accompanied with obesity, might also protect against fracture. On the other hand, clinical observations on diabetic patients suggest that hyperglycemia per se tends to reduce BMD and to increase fracture risk in contrast to the above factors. Thus, BMD and fracture risk in patients with the metabolic syndrome may be determined by the balance between beneficial effects of obesity and dyslipidemia versus detrimental ones of hyperglycemia on bone.