Medical treatment is the elective therapy for patients with gastrinoma when the tumor is not found at surgery or is unresectable or when there is a metastatic disease. H2-blockers and omeprazol are able to control gastric acid secretion and, in addition, somatostatin analogues decrease gastrin levels. A new long-acting and slow release formulation of a somatostatin analogue (lanreotide, SR-L) has been developed. We treated two patients suffering from gastrinoma, total gastrectomy and hepatic metastases with 30 mg intramuscular injections of SR-L every 15 and 10 days, respectively, for a seven-month period. After the treatment, gastrin levels decreased from 35,494 and 15,086 ng/l to 3,211 and 167 ng/l (92 and 98% below pre-treatment levels) in case 1 and 2 respectively, with a relief of symptoms and no side effects.