Data on the prevalence of benign and malignant nodular thyroid disease in patients with acromegaly is a matter of debate. In the last decade an increasing incidence of thyroid cancer has been reported. The aim of this study was to evaluate the prevalence of goiter, thyroid nodules and thyroid cancer in a large series of patients with acromegaly with a cross-sectional study with a control group. Six Spanish university hospitals participated. One hundred and twenty three patients (50% men; mean age 59±13 years; disease duration 6.7±7.2 years) and 50 controls (51% males, mean age 58±15 years) were studied. All participants underwent thyroid ultrasound and fine needle aspiration. Cytological analysis was performed in suspicious nodules between 0.5 and 1.0 cm and in all nodules greater than 1.0 cm. Goiter was more frequently found in patients than in controls (24.9 vs. 8.3%, respectively; p<0.001). Nodular thyroid disease as well as nodules greater than 1 cm were also more prevalent in acromegalic patients (64.6%, vs. 28.6%, p<0.05 and 53.3 vs. 28.6%, respectively; p<0.05), and all underwent fine needle aspiration. Suspicious cytology was detected in 4 patients and in none of the controls. After thyroidectomy, papillary thyroid carcinoma was confirmed in two cases (3.3% of patients with thyroid nodules), representing 1.6% of the entire group of patients with acromegaly (2.4% including a case with previously diagnosed papillary thyroid carcinoma). These data indicated that thyroid nodular disease and cancer are increased in acromegaly, thus justifying its routine ultrasound screening. © 2014 Reverter et al.