This paper reports metabolic data of 24 women and two men, 44-66 years old, ex-residents in an area of endemic fluorosis close to Bahía Blanca city. Fasting fluoremias of these subjects (0.5 to 9.2 microM) and daily urinary fluoride excretion (> 60 mumoles/day) are characteristics of zones with endemic fluorosis. Bone mineral density (BMD) at the lumbar spine (L2-4 1330 +/- 41 mg/cm2) and femoral neck (1045 +/- 10 mg/cm2) were significantly above average of normal subjects of the same age and sex. A significant correlation was observed between the daily excretion of fluoride and BMD L2-4 (r = 0.43, P < 0.05). The Area Under the Curve of insulin during a standard glucose tolerance test showed an inverse relationship with fluoremia. This observation coincides with experiments published elsewhere indicating that fluoride intake at concentrations 5 microM or greater, inhibits the secretion of insulin.