During the past few years, there has been increasing interest in functions that growth hormone (GH) may play in the central nervous system. Accumulating evidence that the hormone may pass the blood-brain barrier and the psychological improvements seen in adults following GH therapy have received particular attention. This paper will review our recent studies on GH receptors in the human and rat brain. A recent study on the effects of GH treatment in adult growth hormone-deficient patients on quality of life and cerebrospinal fluid levels of various hormones and neurotransmitters is also included.