For more than 35 years, growth hormone (GH) has been used to promote l
inear growth in GH-deficient children. Previously, GH replacement in a
dults was limited to the supply of human pituitary-derived GH. In addi
tion, until recently, GH replacement was not deemed clinically indicat
ed. With the introduction of recombinant human prion-free GH, replacem
ent therapy in GH-deficient adults has become feasible, and its use ha
s burgeoned. In this review, recent studies on GH therapy in healthy a
nd GH-deficient adults are evaluated to provide a rational basis for t
he widened scope of its clinical application.