Our knowledge of the mechanisms involved in the regulation of somatotroph cell growth is scanty and much work is still needed to elucidate the role of different growth factors and the mechanisms involved in oncogene activation in both normal and tumour cell growth. However, there are several recent, important clinical ramifications from our improved understanding of GH neuroregulation. The use of long-acting SS analogues is valuable in the treatment of acromegaly, probably in acute variceal haemorrhage and it also produces symptomatic improvement in patients with vipomas and glucagonomas. GHRH may be of value in the treatment of short stature due to hypothalamic GHRH deficiency but further definitive studies are now required to provide convincing evidence that this line of treatment is of greater benefit than the use of synthetic recombinant human GH. Inhibition of GH release may be of value in prevention of both acute and chronic complications of insulin-dependent diabetes mellitus. The use of cholinergic muscarinic receptor blockade in this context may be particularly useful because of a probably sparing of the counter-regulatory GH response to hypoglycaemia. In view of the relative ease with which nocturnal GH secretion can be abolished, we think it reasonable to consider the possible existence of a permissive or mediating role of GH in other disease states, either directly or by maintaining production of either local tissue or circulating growth factors or both.