Sera from 7 patients with localized and 35 with systemic scleroderma were studied for the presence of fluorescent antinuclear antibodies (FANA) (by indirect immunofluorescence on HEp-2 cells) and antibodies to extractable nuclear antigens (anti-ENA) (by immunodiffusion - ID - and counterimmunoelectrophoresis - CIE). In localized disease, antinuclear autoimmunity was limited to 1 FANA positive serum (14%); in systemic disease, the prevalence of FANA was 94% and that of anti-ENA ranged from 29% to 49% (by ID and CIE, respectively). The commonest ENA system, Scl-70, could be easily detected by CIE, in spite of the reported basic nature of the antigen. The anticentromere antibody occurred only in patients with acrosclerosis (7/26-27%), whereas the association of nucleolar + homogeneous FANA, as well as the anti-Scl-70, were found more frequently in diffuse scleroderma (9/9-100% and 6/9-67%, respectively). The presence of the anticentromere antibody excluded that of any anti-ENA, while a close association was found between nucleolar + homogeneous FANA and the anti-Scl-70. Pulmonary involvement was significantly more frequent in nucleolar + homogeneous FANA positive patients; moreover, in two cases the same pattern proved to predict the development of diffuse scleroderma.