Twenty-four out of 54 patients with primary Sjögren's syndrome (SS) were shown to be positive for IgG and/or IgM anticardiolipin antibodies (aCL). Extraglandular manifestations were related to the IgG-, but not to the IgM-aCL. Twenty SS patients were examined over a 3 year period. Of these, 6 displayed a marked increase in IgG- and IgM-aCL and, among them, 4 developed extraglandular manifestations of SS throughout the follow-up.