Inclusion criteria:

• Male and female patients (> 18 years) with prior surgery of micro- or macroadenoma of the pituitary.
• At least 6 months chronic treatment with 30mg octreotide (long acting release).
• Partial responsiveness, which is defined as follows: at any one point within the 6 months monotherapy with 30mg/month octreotide (long acting release) the patient must have experienced a decrease in GH and IGF-1 of at least 25% as compared to pre-monotherapy values (= baseline). Note: For efficacy analysis GH- and IGF-1-values measured in the central laboratory at visit 1 (=study baseline) will be used.
• Lack of suppression of GH nadir to < 1.0 µg/L, after oral administration of 75 g of glucose (OGTT) and IGF-I levels at least 10% above the normal value ± 2 SD (adjusted for age and gender; Brabant 2003) must be proven within 4 weeks prior to visit 1. However, if acromegaly symptoms are inadequately controlled as defined in the acromegaly comorbidities and symptom evaluation (as judged by the investigator), an abnormal GH or IGF-1-value as defined above is sufficient.
• Patient's written informed consent.

Exclusion criteria:

• Requires surgery for recent significant deterioration in visual fields or other neurological signs, which are related to the pituitary tumor mass.
• Radiotherapy planned or radiotherapy for acromegaly within the last 2 years.
• Symptomatic cholelithiasis that is clinically relevant.
• Receiving treatment with dopamine agonists within the last 6 months or prior treatment with GH-receptor-antagonists.
• Patients with renal insufficiency, Raynaud-Syndrome or gastrointestinal ulcer/ bleeding cannot be included in the study or psychose in anamnesis.

Other protocol-defined inclusion/exclusion criteria may apply