Some drinking waters present levels of sulphates exceeding the EEC standard for drinking water quality (250 mg SO4/l). We designed the present study since very few studies have been carried out to date on the human biological effects associated with water intake of sulphates. On urine collected from 180 school-children, aged 11-14 years, living in two mountain areas of Northern Italy with very different sulphate content (of geological origin) in the water supply (area A: ranging from 275 to 345 mg/l; area B: ranging from 35 to 65 mg/l), inorganic sulphate, calcium, magnesium, sodium and potassium were measured. Data on health conditions and drinking water habits were collected. No significant difference in urinary excretion of sulphate, calcium and potassium was observed between the subjects living in the two examined areas. Urinary magnesium and sodium were lower in subjects from area A than in area B. Urinary sulphates were significantly related with the cations, with the exception of potassium in area A subjects. Our results suggest that the drinking of water with sulphate levels (mainly calcium sulphate) ranging from 275 to 345 mg/l, does not increase the total daily sulphate intake nor seems to significantly affect the urinary parameters investigated.