Growth hormone (GH) is necessary for normal linear growth. Excess secretion of GH induces gigantism in prepubertal children and acromegaly in adults. Acromegaly arises from GH-secreting pituitary adenomas. Syndromes of excessive secretion of GH or acromegaly are caused 95 % of the time by a pituitary adenoma of the somatotrophs. A few cases of ectopic GHRH-producing tumors, usually seen in the lung or pancreas, also have been described. Acromegaly is uncommon, with an incidence of 3-4 cases per million per year. Acromegaly is a severe disease often diagnosed late. Morbidity and mortality rates are high, in particular, because of associated cardiovascular, cerebrovascular, and respiratory disorders and malignancies.