Although 5% of all cases of congenital deafness are caused by Pendred's 
syndrome, there are few reports in the literature. Seven patients with Pendred's 
syndrome in three families living in the same village were detected. For that 
reason, the syndrome is reviewed in light of the literature. The sex 
distribution of the patients with Pendred's syndrome and their families was 
recorded. We tested for thyroxine, triiodothyronine, thyroid-stimulating 
hormone, triiodothyronine resin uptake, and perchlorate, and performed caloric 
testing. In one patient, subtotal thyroidectomy was performed. In the 
histopathologic study, a thyroid nodule filled with colloid was found. 
Chromosome studies showed no anomalies in any patient. Five of the patients were 
deaf-mutes. We observed that the parents were cousins in all three families. 
These families also had healthy children, and the existence of the syndrome in 
both sexes points to an autosomal recessive trait.