Background: Studies comparing primary medical treatment of acromegaly with surgery are often non-randomized, and not stratified by illness severity. We prospectively compared primary medical therapy with pituitary surgery in patients with acromegaly. All patients had macroadenomas, at least one random human growth hormone (GH) level ≥12.5 ng/mL, elevated IGF-I levels and failure to suppress GH to <1 ng/mL during an oral glucose tolerance test (oGTT). Methods: Forty-one patients from seven centers were randomized to primary treatment with octreotide LAR, 30 mg every 4 weeks × 3 months (ARM A, N = 15), or pituitary surgery (ARM B, N = 26) using a 1:2 randomization design. Patients cured by surgery (defined as nadir GH during oGTT <1 ng/mL and normal IGF-I) received no subsequent treatment. Those not cured surgically were then treated with octreotide LAR (SubArm B1) for 3 months. Results: Only one of the 15 patients in ARM A (6.7%) had normalization of both GH and IGF-I. In contrast, 13/26 patients had normalization of both GH and IGF-I after surgery alone (50%). Of the remaining 13 patients who did not normalize with surgery alone, treatment with octreotide LAR resulted in a normal nadir GH and normal serum IGF-I in 7 (53.9%). In total, 20/26 in ARM B (76.9%) experienced normalization of defined biochemical acromegaly parameters. Conclusions: Pituitary surgery alone was more effective than primary medical treatment (p = 0.006), and the combination of surgery followed by medical therapy was even more effective (p < 0.0001). Subjects treated with medical therapy after surgical debulking had a significant improvement in response rate compared to matched subjects treated with primary medical therapy.