Somatostatin analogues are widely employed in the treatment of hypophyseal adenomas. The most widely used analogues at the present time are octreotide and lanreotide. Both are available in slow release formulations using the parenteral route and show a preferential affinity for the sst(2) receptor of somatostatin. Both octreotide and lanreotide have proved their effectiveness in the treatment of GH- and TSH-secretory hypophyseal adenomas. In those patients who respond to pharmacological treatment we often achieve not only the control of hormonal hypersecretion, but also a reduction in the volume of hypophyseal neoplasia. In the other types of hypophyseal adenoma, on the other hand, somatostatin analogues have proved to have little effect: apart from isolated cases of effectiveness in non-functioning adenomas, the administration both of octreotide and lanreotide to patients with Cushing's disease or prolactinoma did not significantly modify the hormonal hypersecretion or tumoural volume. The side-effects of somatostatin analogues are comparatively rare and of moderate entity: only a small percentage of patients requires the treatment to be suspended owing to the occurrence of side-effects. New analogues are currently under study. These have a different receptor profile and they could therefore find new applications in hypophyseal pathology. Octreotide, bound to radioactive substances or to toxins, has also been utilised for the selective destruction of neoplastic tissues expressing the sst(2) receptor of somatostatin.