Respiratory disorders are common complications of acromegaly patients. We conducted a large-scale survey in the patients with acromegaly and demonstrated the characteristics of their lung function and blood gas.A prospective cohort study was conducted with 115 patients with active acromegaly and 56 patients with nonfunctioning pituitary adenomas. All patients underwent clinical, biological, radiological, lung functional and blood gas assessments.Acromegaly patients had a higher lung volume than those with nonfunctioning adenomas (forced vital capacity value (FVC) and FVC% predicted: p < 0.001). The small airway was less obstructive in acromegaly patients (higher FEV1% predicted, PEF% predicted, MEF75% predicted, MEF50% predicted, MEF25% predicted: p ≤ 0.001 for all analyses, FEV1/FVC: p = 0.151). The average partial pressure of carbon dioxide in acromegaly patients was higher (p < 0.001), but there was no significant difference in the average partial pressure of oxygen or oxygen saturation between the two groups (p > 0.05). In acromegaly patients, the average age of patients with small airway obstruction was higher than that of patients with normal lung function (p < 0.05), but no significant difference in GH or IGF-1 levels between the two groups were found (p > 0.05).The acromegaly patients in this cohort had increased lung volume. However, there was no evidence demonstrating hypoxemia in acromegaly patients. The small airway was less obstructive in acromegaly patents. Small airway obstruction was observed in elderly patients with acromegaly.