Lung involvement frequently complicates systemic sclerosis (SSc), provoking loss of quality of life and a poor expectation of survival. For this reason an early diagnosis of lung involvement is warranted: high-resolution computed tomography (HRCT), pulmonary function tests (PFT), lung scintigraphy with DTPA and bronchoalveolar lavage (BAL) are mandatory to define and follow-up pulmonary interstitium. Coughing and a sensation of breathlessness on exertion are the earliest symptoms of lung involvement. Lung involvement may be investigated with PFTs, which are non-invasive and require breathing into a tube via a mouthpiece. Forced vital capacity, which measures the total amount of air capable of being blown forcefully, and the diffusion capacity for carbon monoxide, a measure of how well oxygen diffuses into blood, are the most important functional measures. A routine chest X-ray may demonstrate fibrosis, but it is not very sensitive for detecting early or mild disease. For this reason, a HRCT scan is required. This non-invasive investigation provides images of multiple slices through the lung, from top (apex) to bottom (base), and can even detect lung involvement in early phases when no symptoms are present. (99m)T-DTPA is recommended in those patients with isolated diffusion deficits on lung function tests and in addition to HRCT in confirming the suspicion of vascular disease rather than early fibrosing alveolitis. Bronchoscopy with BAL is an invasive test that also may provide information about the inflammatory status of the affected areas of the lung detected during HRCT. In order to detect alveolitis, it should be performed as early as possible, to start prompt immunosuppressive treatment.