In secreting islet cell carcinoma, the long-acting somatostatin analogue, Sandostatin, reduces symptoms of endocrine secretion both by inhibiting peptide secretion and by acting on the target organs. It could be used during the initial evaluation of patients with such tumors and thereafter when the tumor cannot be found or is metastatic. Its efficacy depends upon the tumor type and probably the presence of somatostatin receptors on the tumoral cells. It could decrease with time, especially in VIPomas. Side effects are few and usually mild. Hypoglycemia attacks in insulinoma could be worsened during treament by the the complete inhibition of hyperglycemic hormones. The inhibition of tumoral growth, based on animal models, appears infrequent in clinical practice.