Background: Pulmonary arteriovenous malformations (PAVMs) are present in approximately 15-50% individuals with hereditary hemorrhagic telangiectasia (HHT). They may be isolated but more often are multiple. The goal of this study was to evaluate the influence of PAVMs on lung mechanical properties. Methods: We reviewed the files of all adult patients (age >= 18 years) referred to our Center for evaluation of HHT between 2005 and 2013. The diagnosis of HHT was based on the Curacao criteria and/or the presence of a pathogenic mutation. Exclusion criteria included: chronic cardiac or lung disease (i.e. asthma or COPD), suspicion of pulmonary hypertension on echocardiography, current or past smoking (>10 pack-years), history of thoracic surgery, previous treatment of PAVMs by embolotherapy, lung infection or thromboembolic disease in the past 3 months, pregnancy and obesity (BMI >30 kg/m(2)). Chest high resolution CT-scan and pulmonary function tests were performed the same day in all patients as part of our routine work-up. Results: One hundred and fifty five patients with HHT were included (age: 44.4 +/- 16.7 yrs - mean +/- SD -; males: 39%). Eighty eight patients had no PAVM, 45 had 1-3 PAVMS and 22 had at least 4 PAVMs. Thirty eight patients had unilateral PAVMs and 29 bilateral PAVMs. We found no statistical relationship between the number, the size and the laterality of PAVMs and results of lung flows and volumes. Conclusion: We found no evidence that PAVMs have a significant influence on lung mechanical properties as measured using routine pulmonary function tests in adult patients with HHT, even in case of numerous, macroscopic or bilateral malformations.