Urinary iodine excretion (UIE) was measured on urine samples collected in the morning from 3480 subjects (both adults and children) living in an extended territory of Campania region including urban and extraurban areas, in the period 1993-96. UIE was measured by an autoanalyzer (Bran + Luebbe) and expressed as microgram/l. Means UIE were significantly lower in the patients living in the villages of Avellino (65 +/- 48), Benevento (44 +/- 44) and Caserta (78 +/- 53) respect to the control subjects from the area of Naples (102 +/- 66). These data demonstrate that in many areas of our region a mild-moderate iodine deficiency is still present as indicated by a low urinary iodine excretion and therefore an effective program of iodoprophylaxis is fundamental in this region.