The occurrence of thyroid disorders is connected with iodine deficiency, defective synthesis or releasing of thyroid hormone and endemicity. Genetic factors are known as a single gene defects, interaction of multiple genes with environmental factors, as well as chromosomal aberrations. Diofnosis thyroid disorders is enforced by I-131 uptake test, thyroid scanning with I-131 or Tc- 99m and serum radioimmunoassays of T3, T4, free T4 and TSH. They were largely classified as hypothyroidism, hyperthyroidism, simple goiter and normal. The pedigree of 58 families was drawn by propositus, and then the correlation between thyroid disorders and TSH levels was analyzed. The results are as follows: 1) The offsprings and their mothers of 15 families were hypothyroidism, THS level was 5 folds for offsprings and 4 folds for mothers in comparison with control group. 2) 13 families were hyperthyroidism in siblings but their mothers were normal in thyroid function, TSH level of the siblings was lower than control group. 3) Though the offsprings and their mothers of 10 families were similar to TSH level of control group, they are all simple goiter, familial thyroid disorders, in other thyroid function test. The familial thyroid disorders suggested that these transmitted from mothers to offsprings with X-linked dominant or autosomal dominant inheritance.