Urine fluoride excretion was evaluated in a group of children aged 12–14 years in the frame of the iodine and fluoride intake promoting intervention in the district of Frýdek-Místek in years 1997–1999. The average level of urinary excretion of fluoride amounted in the onset of study to 0.574 mg/l and decreased significantly by the year 1999 to 0.201 mg/l. The decrease of urinary fluoride content is explained either by the increased fluoride clearance from previously saturated skeleton (due to the water fluoridation history of the district) in the onset of study and/or by the insufficient availability of alimentary fluorides (especially fluoridated salt) during the fluoride intake promoting intervention.

        Key words: urine fluorides – age 12–14 years – preventive program