IntroductionInterstitial lung diseases (ILDs) primarily affect the interstitium, an alveolar wall tissue between the capillary endothelium and the alveolar epithelium. The term 'interstitial,' however, is misleading since alveolar spaces, peripheral airways, and vessels can be involved in most of these disorders. They often require a multidisciplinary diagnosis i.e., an integration of clinical, radiological, and pathological findings. A chest radiograph is relatively insensitive because of nonspecific patterns.Generally, these disorders can progress to irreversible pulmonary fibrosis and are an important cause of morbidity and mortality. It is critical to make a prompt and accurate diagnosis of the underlying causes so that patients can be managed appropriately. ILD is subdivided into idiopathic interstitial pneumonia, of which idiopathic pulmonary fibrosis (IPF) is one subset, and diffuse parenchymal lung diseases, which may be secondary to a variety of occupational or environmental exposures or others. They can complicate multiple rheumatic or connective tissue diseases (CTDs). Apart from ILD, other forms of lung damage involving the pleura, vasculature, airways, and lymphatic tissue can complicate CTDs. AimsAims include studying the role of high-resolution computed tomography (HRCT) in diagnosing various ILDs based on morphologic patterns, evaluating the correlation between ILD and various connective tissue disorders and the prevalence of complications in such patients, and evaluating the association of smoking with various ILDs. MethodsThis is a retrospective study in which HRCT thorax was performed on a 128-slice Philips CT scanner machine on 50 patients from December 2020 to February 2022 in SVP Hospital, Ahmedabad. No age or gender bias was followed.