The purpose of this study is to compare the safety and tolerability of combination therapy with Sandostatin LAR plus Pegvisomant to that of Sandostatin LAR alone or Pegvisomant alone.

Inclusion Criteria:

• Diagnosis of acromegaly
• Received previous radiation and/or surgical treatment for their GH (Growth Hormone) producing pituitary adenoma and have required medical therapy due to failure to normalize GH (Growth Hormone) and/or IGF-I as a result of their primary treatment
• Patients that been receiving Sandostatin LAR for a minimum of 6 months prior to enrollment

Exclusion Criteria:

• Presence of other conditions that may result in abnormal GH (Growth Hormone) and/or IGF-I concentrations
• Patients on current medical therapy other than Sandostatin LAR
• AST/ALT >= 3xULN (upper limits of normal)
• Pituitary adenoma within 3mm of optic chiasm confirmed by recent MRI
• Visual field defects (except post-surgical stable residual defects)
• Unable to self administer drug
• Radiotherapy within 12 months of entering the study