Ultrasonography is an excellent and objective method for assessing thyroid volume, especially in children where clinical evaluation is inaccurate. The aim of this study was to evaluate the presence of goiter by thyroid ultrasound and palpation in 244 schoolchildren, 6 to 14 years old, living in some rural villages of Val Sarmento, a mountain area of Basilicata, Italy. In 1996 we revealed the presence of endemic goiter in 25% of the schoolchildren evaluated by palpation, according to World Health Organization (WHO) criteria, and in 15.9% of the schoolchildren evaluated by ultrasonography (7.5 MHz linear probe). The median urinary iodine excretion, taken from an extemporaneous sample of the first urines in the morning, was 62.2 microg/l. This study includes Val Sarmento, an area with mild-moderate grade (Grade I) of iodine deficiency, suggesting the need for iodine prophylaxis. Furthermore, it proves that the measurement of thyroid volume by ultrasonography is an essential instrumental method for a correct epidemiological study of endemic goiter, particularly in areas where there is mild iodine deficiency.