Lung involvement is common in patients who have complications of connective tissue disease (CTDs) and causes considerable morbidity and mortality. High resolution CT (HRCT) has a pivotal role in the detection of lung fibrosis. In patients who have coexistent pathologic processes, HRCT often allows the predominant process to be identified. HRCT has an important role in detecting possible complications such as opportunistic infection or the development of malignancy. However, the limitations of HRCT should not be overlooked. In many cases, HRCT appearances are nonspecific and may or may not be related to an underlying CTD. Thus, radiologic findings should never be interpreted without knowledge of the clinical picture.