Neurological disturbances frequently emerge in antiphospholipid syndrome (APS). One hundred and twenty four patients (100 women, 24 men, mean age 37.5 +/- 11.3 years) with primary APS (PAPS), including 76 patients with Sneddon's syndrome and positive antibodies to phospholipids (aPL), have been studied. A structure of neurological disturbances was as follows: ischemic lesions of cerebral blood flow (LCBF) which comprised stroke and transient LCBF (91%); thrombosis of brain venous sinuses (3%); epileptic seizures (24%); headache (65%); chorea (15%); visual neuropathy (9%); peripheral neuropathy (6%); multiple-sclerosis-like syndrome (10%); myasthenia syndrome (1%); syndrome of parkinsonism of non-vascular genesis (1%) and psychotic disorders (2%). 84% patients had main systemic APS symptoms (fetal loss, thrombosis), which preceded neurological appearances in 78% cases. All the patients had aPL: aPL to cardiolipin (aCL) and/or lupus coagulant (LC) and/or aPL to phosphatidyl serine, phosphatidyl inositol, phosphatidyl ethanolamine. In some patients, aCL titres ranged from positive to negative values and LC was not consistently detected. Thus, the presence of clinical symptoms of PAPS including neurological disturbances demands an investigation of different aPL types as well as a replicate study for immunological confirmation of PAPS.