In 28 patients with systemic sclerosis interstitial lung involvement was investigated with high-resolution Computed Tomography (HRCT) in comparison with other diagnostic methods (respiratory function tests, lung scintigraphy and conventional radiography of the chest). The most frequent CT signs were: interlobular septal thickening, intralobular interstitial thickening, and ground-glass density. Their distribution was generally basal and posterior and high correlation was observed between the extent of lung disease and the cutaneous pattern of scleroderma. Pathological findings were present in 93% of cases: HRCT can must be considered more effective than the other methods in the evaluation of systemic sclerosis and should therefore be a fundamental diagnostic tool in the study and follow-up of interstitial diseases in the patients with systemic sclerosis.