Growth hormone deficiency is commonly associated with pituitary disorders. A variety of medical conditions, pituitary and parasellar tumors themselves, or the therapies associated with them, can lead to growth hormone deficiency in adulthood. This chapter reviews the methods used to diagnose growth hormone deficiency and the potential benefits that may be seen with growth hormone replacement. The potential safety concerns associated with growth hormone replacement including concerns regarding glucose metabolism, tumor growth, and secondary malignancies are also reviewed. Guidance is also given regarding the initiation of growth hormone in terms of dosing, and techniques to avoid side effects. © 2013 John Wiley & Sons, Ltd..