Dilatation and oesophageal body aperistalsis in achalasia can lead to stasis which in turn can induce repeated microaspiration. It is therefore conceivable that patients with achalasia may also have abnormalities in lungs secondary to repeated episodes of microaspiration. There is a lack of systematic study on involvement of lungs in patients with achalasia. Thirty patients with achalasia underwent pulmonary function tests (spirometry, and carbon mono-oxide diffusion capacity) and high resolution computerized tomography (HRCT) of the chest. The mean age of patients and mean duration of disease were 33.5 +/- 10.9 years and 28.1 +/- 27.3 months respectively. Regurgitation was present in 22 (73.3%) of them. Respiratory symptoms in them were dry cough in 17 (56.6%), and chest pain in 18 (60%). The oesophagus was dilated in 26 (86.6%) and 13 (43.3%) had residue in oesophagus. Sixteen (53.3%) patients had either anatomical changes as seen on HRCT or functional changes as observed on pulmonary function tests. Of those with functional abnormalities, five (16.6%) and one (3.3%) had restrictive and obstructive airways disease respectively. While evidence of tracheo-bronchial compression by dilated oesophagus was present in eight (26.6%), 10 (33.3%) patients had parenchymal lung disease [nodular opacities in five (16.6%), ground glass appearance six (20%), patchy pulmonary fibrosis five (16.6%), air trapping two (6.6%), consolidation and bronchiectasis one (3.3%) each]. There was a significant association between presence of regurgitation and dilatation of oesophagus (P = 0.032). More than half (53.3%) of patients with achalasia have structural and/or functional abnormalities in lungs.