The purpose of the study is to determine if Pegvisomant is more efficacious than Sandostatin LAR Depot in normalizing IGF-I levels in treatment naive patients with acromegaly.

Inclusion Criteria:

• Diagnosis of acromegaly
• IGF-I levels >=1.3xULN (upper limit of normal) at screening
• No history of radiotherapy or prior treatment with other drugs for acromegaly
• Minimum of two months must have elapsed post surgery prior to screening

Exclusion Criteria:

• Presence of other conditions that may result in abnormal GH (Growth Hormone) and/or IGF-I concentrations
• AST/ALT >= 3xULN (upper limit 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