CONTEXT: Cross-sectional studies showed an elevated prevalence of vertebral fractures in acromegaly. However, no data are available on incident vertebral fractures in this clinical setting. OBJECTIVE: The objective of the study was to investigate the incidence and risk factors of vertebral fractures in patients with acromegaly. DESIGN: This was a 3-year prospective study. SETTING: The study was conducted at referral centers. SUBJECTS: Eighty-eight patients with acromegaly (33 females, 55 males; mean age 50 years, range 21-85 years) and 106 control subjects, matched for sex and age (43 females and 63 males, mean age 55 years, range 33-79 years), attending outpatient bone clinics participated in the study. MAIN MEASURES: Patients and control subjects were evaluated for the incidence of vertebral fractures using a quantitative morphometric approach on spine x-ray, which was performed at baseline and after 3 years of follow-up. At the same time points, patients with acromegaly were also evaluated for bone mineral density with dual-energy X-ray absorptiometry at lumbar spine and femoral neck. RESULTS: After a 3-year follow-up, 37 patients with acromegaly (42.0%) and 4 control subjects (3.8%) experienced incident vertebral fractures (P < .001). The incidence of vertebral fractures was significantly higher in patients with active disease as compared with those who had controlled/cured acromegaly at the study entry (62.5% vs 25.0%; P < .001). The risk of incident vertebral fractures was significantly associated with hypogonadism, a change in the femoral neck bone mineral density, and prevalent vertebral fractures at the study entry only in patients with controlled/cured acromegaly, whereas in patients with active disease, the fracture risk was not influenced by the above-mentioned clinical factors, but it was significantly associated with the duration of active acromegaly. CONCLUSIONS: This prospective study demonstrates a high rate of incident vertebral fractures both in patients with active and controlled acromegaly.