A girl with type 1a pseudohypoparathyroidism (PHP) presented several hormonal abnormalities. Although she had eluded neonatal thyroid screening, she was diagnosed as having hypothyroidism at the age of 5 months. Thereafter, a diagnosis of PHP was made on the basis of skeletal features of Albright osteodystrophy and lack of both cyclic adenosine monophosphate (c-AMP) and phosphaturic responses after parathyroid hormone (PTH) infusion. The basal levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were higher than normal and showed exaggerated responses to luteinizing hormone-releasing hormone (LH-RH). There was no growth hormone (GH) response to arginine infusion, and the prolactin (PRL) response after thyrotropin-releasing hormone (TRH) infusion, was also impaired. The stimulating guanine nucleotide-binding protein (Ns) activity of the erythrocytes was reduced to 66.9%. The skeletal age was not delayed at the age of 5 months in spite of the hypothyroid state, and it advanced following thyroxine and vitamin D treatments.