Hyperthyroidism in children is a rather rare disease. Occasionally a single case is reported, but most of the cases have been reported from the larger clinics. Dinsmore1 of the Cleveland Clinic reported forty-eight cases in patients ranging up to 17 years of age, while Helmholz2 reported thirty from the Mayo Clinic. Greene and Mora3 from Richter's service reported twenty-six cases in their series, the ages ranging from 8 to 16 years inclusive. This represented 2.1 per cent of their 1,200 consecutive cases that came to operation. Twenty-two of these patients were girls and four were boys. One child, a girl, was 8 years old, two were 11, and one was 12; the rest of the patients were fairly evenly scattered over the next four year period. Cowden, reviewing the literature in 1923, found no case of hyperthyroidism in a boy under 10 years of age.