The recovery of acromegaly is not obtained in about 50 percent of cases treated with radiotherapy and/or transsphenoidal surgery. Somatostatin analogs prescribed in such cases are effective but need either several subcutaneous injections a day or continuous infusions with pumps. Long-acting formulations of the new somatostatin analog lanreotide should avoid such drawbacks. Nine acromegalics, not cured by pituitary surgery (associated with radiotherapy in 7) received on IM injection of a long acting formulation of lanreotide twice a month for one year. Basal evaluation included: clinical examination, routine analyses, gall bladder ultrasonography, hormonal investigation of pituitary function including GH and IgF-1 measurements, visual field evaluation and pituitary scanning. A similar evaluation was performed on months 6 and 12 of treatment. The clinical symptoms of acromegaly progressively improved during therapy. Plasma GH levels decreased significantly (P < 0.01) from 24.2 +/- 2.1 to 9.3 +/- 1.2, 6.4 +/- 1.4 and 7.9 +/- 1.1 micrograms/l on months 3, 6 and 12, respectively. Plasma IgF-1 levels were normalized, decreasing from 676 +/- 40 to 331 +/- 30, 350 +/- 36, and 317 +/- 29 ng/ml on months 3, 6 and 12, respectively. Plasma lanreotide levels remained stable throughout the treatment. Side-effects included slight and transient diarrhoea and abdominal cramps which disappeared after 6 months of treatment. No gallstones appeared during treatment. These results show that one injection, twice a month, of a long-acting formulation containing 30 mg lanreotide is able to control the evolutivity of acromegalies not cured by pituitary radiotherapy and/or transsphenoidal surgery. Such formulations are well tolerated and avoid the drawbacks of either several subcutaneous injections a day or continuous infusions of somatostatin analogs.