Two new cases of pseudohypoparathyroidism are described, in each of which there was a selective deficiency of thyrotropin. Hypothyroidism is very common in pseudohypoparathyroidism and, in all cases appropriately studied thus far, appears attributable to a probable deficiency of thyroid stimulating hormone (TSH). Thyroid function should be evaluated in all patients with pseudohypo-parathyroidism and appropriate replacement therapy should be given when indicated. There was no evidence of resistance to hormones other than parathyroid hormone. Calcium balance was strongly positive. Parathyroid hormone could not be detected in the serum by radioimmunoassay. A chromosomal abnormality, clearly unrelated to pseudohypoparathyroidism, was present in one patient. © 1969.