The results of investigations for antinuclear antibodies in scleroderma and other connective diseases are reported. An indirect fluorescence method on Hep-2 cell smears was used. Antibodies directed against chromosomal centromeres were detected in 25 cases: 19 sera of patients with diffuse scleroderma, 2 cases of Raynaud's disease, 2 cases of rheumatoid arthritis and 1 case each of lupus and dermatomyositis. A significant correlation was found between the presence of anticentromere antibodies and benign forms of scleroderma, notably the CREST syndrome.