The occurrence of a bizarre familial syndrome combining deaf-mutism, stippled epiphyses, goiter and abnormally high PBI in 2 of 6 children of a consanguineous marriage is described. Mean PBI levels were 14 and 21 μg/100 ml; BEI 9 and 15 μg/100 ml; T₄-by-column 11 and 14 μg/100 ml; 24-hr ¹³¹I uptake 49 and 70%; 24-hr PB^13lI conversion ratios 40 and 41%; thyro-binding index 0.81 and 0.93; TBG 17 and 20 μg/100 ml; antithyroglobulin titer less than 1:16. Potassium perchlorate discharge test was normal. Iodine metabolism studied in one subject revealed thyroid iodine clearance of 24 ml/min and renal clearance of 26 ml/min. Urinary iodide excretion was 294 υg/day, and PB¹³¹I was over 70% as T⁴. The T⁴ was identified on paper chromatography in 3 solvent systems. The free thyroxine level was 4.9 mμg/100 ml. An infant of 8 weeks had a mean PBI of 19.3 μg/100 ml, TBG of 15.8 μg/100 ml, and presumably also has the syndrome. Another sib had a mean PBI of 11 μg/100 ml. Two sibs and the parents are normal. A hypothesis is advanced suggesting the possibility of inhibition of thyroid hormone transport into tissue, or end-organ resistance to the hormone in view of the eumetabolic state of the subjects in the presence of high circulating levels of blood thyroxine and normal thyroxine binding capacity.