Antinuclear antibodies (ANA) by the indirect immunofluorescence method and their immunospecificities were investigated in 60 patients with rheumatoid arthritis using HEp-2 cells as substrates. ANA were detected in 35% of the patients. The patterns of nuclear staining observed included: diffuse or patchy homogeneous (20%), speckled (8.3%), centromere (3.3%), nucleolar (1.6%) and in 1 patient a mixed pattern (1.6%). The presence of antihistone antibodies (20%) correlated with the presence of an homogeneous pattern on the HEp-2 cells.