Infantile systemic hyalinosis is an autosomal recessive disorder characterized by diffuse hyaline deposits in the skin, gastrointestinal tract, muscles and glands. The molecular basis of infantile systemic hyalinosis is unknown. The main pathological feature is widespread hyalinosis of many tissues and organs. We present an 18 month-old girl with infantile systemic hyalinosis and hypothyroidism. Newly diagnosed children with infantile systemic hyalinosis should have thyroid studies as a routine part of diagnostic work-up.