Neurologic complications of both the central and peripheral nervous systems occur frequently in patients with primary Sjögren's syndrome (primary SS), but the underlying cause of these complications is unknown. We studied the presence of antineuronal antibodies in relation to neurologic complications in a consecutive series of 45 patients with primary SS. Twenty-five patients had neurologic complications: 12 patients with polyneuropathy, three with psychiatric disorders, four with carpal tunnel syndrome, seven with migraine, seven with myalgia, and four with other complications (transverse myelitis, stroke, Bell's palsy, and pyramidal signs). Ten patients had more than one neurologic complication. Eleven patients had major and 14 had minor complications according to criteria used for rating neurologic complications in patients with systemic lupus erythematosus. Antineuronal antibodies were present in six of 11 (55%) patients with major neurologic complications and in four of 34 (11%) of patients without major neurologic complications (p = 0.001). This difference could be attributed mainly to the group of patients with polyneuropathy. Three of the 10 sera of patients with positive antineuronal antibodies had antibodies reacting with a 38-kd neu-ronal protein on immunoblotting, identical to the anti-Hu antibody reactivity in paraneoplastic neurologic disease associated with small-cell lung cancer.