Polyglandular autoimmune syndromes (PGA) are uncommon constellations of organ-specific autoimmune diseases, characterized by the existence of more than one autoimmune disease in an affected individual. PGA type II (Schmidt’s Syndrome) is characterized by the association of autoimmune Addison’s disease with thyroid autoimmune diseases and/or type 1 diabetes mellitus. Here, we report a 12.5 years old girl who applied to our clinic with the complaint of hyperpigmentation of the skin, malaise for the last 5 months and also suffering from dizziness and excessive sweating. Adrenal insufficiency was thought to be the diagnosis. Further laboratory tests revealed an increased basal ACTH level, and a blunted cortisol response to ACTH stimulation. Autoantibodies against thyroid and adrenal gland were elevated. Therefore, she was diagnosed as PGA type II autoimmune thyroiditis and autoimmune Addison’s disease. Polyglandular autoimmune syndrome type II which usually being in older age groups, is very rare at this age. Early recognition of these components of the syndrome and replacement therapy can be life saving, particularly when there is adrenal or thyroid insufficiency.