The regional screening program for congenital hypothyroidism (CH) in Riyadh Province was started as a pilot study in December 1988. By September 1990, the program covered all deliveries at the Ministry of Health (MOH) and King Saud University hospitals. The program utilizes cord serum thyroid-stimulating hormone (TSH) with a low recall rate of 0.1%. The average cost per specimen was SR 12 (US$ 3.20). Among 283,647 infants screened, 83 infants were confirmed to have CH (incidence 1:3417). In 17 infants, however, the diagnosis was not confirmed due to difficulties in recall. Eleven infants with cord serum TSH of more than 100 mU/L proved to be clinically and biochemically euthyroid at recall. Three of these were secondary to maternal proplthiouracil (PTU) therapy. The female to male ratio was 1.5:1. The majority of infants lacked clinical symptoms and signs of hypothyroidism. Thyroid scans showed the most common etiology to be thyroid ectopy (50%), followed by dyshormonogenesis (26%) and athyrosis (24%). Although there was no significant difference in the mean cord T4 values among the different groups, the mean T4 value at recall in the athyrotic group was significantly (P <0.001) lower than the cord results (14.8 versus 62.7) and that is of recall for the ectopic and dyshormonogenesis groups (14.8 versus 47.0 and 51.3 respectively0. There was bo significant difference in the mean TSH among the different groups in the cord and recall samples. Skeletal maturation was more delayed in the athyrotic group. The mean age at the time of recall was 16.4 days (range 4 to 64), and the mean age at the start of therapy was 17.8 days (range 5-64).