Interstitial pulmonary fibrosis is a common feature of scleroderma (systemic sclerosis) which may result in impairment of pulmonary function and may be a major determinant of morbidity and mortality. Clinicopathologic observations suggest that interstitial and alveolar inflammation may appear prior to fibrosis. Using the bronchoalveolar lavage (BAL) technique, we have characterized the nature of the inflammatory process in the lower respiratory tracts of 19 non-smoking scleroderma patients. Eleven of 19 patients (58%) had increased percentages of neutrophils and/or eosinophils in BAL fluid. Five of 10 patients (50%) had elevations of IgG in BAL fluid. The presence of neutrophils was associated with a decreased lung diffusing capacity for carbon monoxide (P less than 0.05) and with more advanced radiographic features of interstitial fibrosis in patients with disease of more than 1 year's duration. This study suggests that scleroderma lung involvement may be characterized by an inflammatory alveolitis and that the presence of such inflammation may relate to the severity of the pulmonary disease.