<p class="abstract"><strong>Background:</strong> The auto-immune connective tissue diseases (AICTD) are polygenic clinical disorders having heterogeneous overlapping clinical features. Certain features like autoimmunity, vascular abnormalities, arthritis/arthralgia and cutaneous manifestations are common to them. Lung involvement can present in AICTDs in form of: pleurisy, acute/ chronic pneumonitis, pulmonary artery hypertension (PAH), shrinking lung syndrome, diffuse alveolar damage, pulmonary embolism (PE), bronchiolitis obliterans organizing pneumonia, pulmonary infections, cardiogenic pulmonary edema, etc. High-resolution computed tomography (HRCT) plays an important role in identifying patients with respiratory involvement. Pulmonary function tests are a sensitive tool detecting interstitial lung disease.</p><p class="abstract"><strong>Methods:</strong> The present study is an observational study carried out on 170 patients of AICTD in department of Dermatology, Venereology and Leprosy at a tertiary care centre during a period of 2 years from October 2017 to August 2019. Detailed history, examination and relevant investigations like chest X-ray, pulmonary function test (PFT), HRCT thorax were done as indicated.<strong></strong></p><p class="abstract"><strong>Results:</strong> The overall incidence of respiratory involvement was 56.7% with maximum involvement in systemic sclerosis cases (82.8% of cases). 45.7% of patients of systemic lupus erythematosus had respiratory involvement, most common being pleural effusion in 11.5%. Impaired PFT’s were seen in 82.8% cases of systemic sclerosis (SSc) and all cases of UCTD. Interstitial lung disease was seen in 34.7% and 25% cases of SSc and DM respectively. PAH was found in 15.2% cases of SSc and 9.8% cases of mixed connective tissue diseases.</p><p class="abstract"><strong>Conclusions:</strong> AICTD are multisystem disorders in which pulmonary involvement can be an important cause of morbidity to the patient and early detection is necessary for prevention of long-term respiratory complications.</p>