We report an 18-year-old man with the unusual combination of Rothmund-Thomson syndrome (RTS) and Addison disease. He was admitted when he was 26 months old because of short stature, dehydration, metabolic acidosis, hyperpigmentation, and typical skin lesions. Because his growth remained delayed, at age 10 years he was given a trial of recombinant growth hormone. After six years of treatment no improvement in height, bone, or sexual maturation was observed. This fact may be related to a defect in connective tissue metabolism. Chromosomal analysis of peripheral blood lymphocytes revealed increased numbers of breaks and gaps. Fibroblasts cultured from affected skin did not grow. Patients with RTS are prone to developing cancer, but no malignant disease was found in our patient. Early diagnosis and treatment of both endocrinologic and malignant complications are essential for survival of patients with this rare syndrome.