We examined 107,670 infants born in the Italian region Emilia-Romagna. Capillary blood samples for contemporary T4 and TSH radioimmunoassay were collected on the 3rd, 4th, 5th, 6th, 7th or between the 7th and the 15th day of life on filter paper. In our method the threshold value for recall for a second assay was calculated taking into account the mean - 2 SD of each session for T4, and fixing between 30 and 50 microU/ml the threshold value for TSH. The re-call percentage was 0.74%. 21 subjects confirmed to be affected by congenital hypothyroidism; this corresponds to a frequency in our region of 1 case every 5,127 infants. 12 subjects had a TBG deficiency, this corresponds to a frequency of 1 case every 8,972 infants. No cases of secondary hypothyroidism were found up to date.