A 54-year-old woman was admitted to our hospital for detailed examination of acromegaly because she noticed bilateral hand and finger swelling at the age of 43 and plantar thickening, facial changes and unclear articulation at the age of 49. She had prominent brow ridges, mandibular protrusion, and enlargement of the hands, feet, nasal wings, lips and tongue. Her growth hormone (GH) level was 39.8 ng/ml, insulin-like growth factor-1 (IGF-1) level was 717 ng/ml, GH level was not suppressed (22.9 ng/ml) during a 75-g oral glucose tolerance test (OGTT). Radiography showed cauliflower-like enlargement of the distal phalanx of the fingers, thickening/enlargement of the plantar soft tissues, and increased antero-posterior diameter of the sella turcica. Magnetic resonance imaging showed a mass (21×17 mm) growing towards the right suprasellar region and invading the cavernous sinus. She was diagnosed with acromegaly based on the characteristic physical findings, GH excess, high IGF-1, lack of GH suppression during the 75-g OGTT, and the presence of a pituitary tumor. She was started on octreotide long acting release (Oct-LAR) 20 mg/4w for tumor shrinkage. After three doses, her GH and IGF-1 levels decreased to 2.19 ng/ml (1.69 during the 75-g OGTT) and 205 ng/ml, respectively, meeting cure criteria for acromegaly. In this case, a decrease in GH and IGF-1 levels, tumor shrinkage, and resolution of cavernous sinus invasion allowed the patient to undergo surgery with curative intent (the first-line treatment for acromegaly) without postoperative complications. Thus, preoperative Oct-LAR administration has the potential to improve treatment outcomes of acromegaly.