Sixty SLE patients with only primary neuropsychiatric manifestations (NP-SLE), (54 female and six male; mean age 44.5) were compared consecutively. Forty-six of the patients (78.3%) were presented with a combination of neuropsychiatric symptoms. Except for the standard immunoserological test, all patients underwent clinical, neurological and psychiatric examination, electrophysiological tests [EEG (electro-encephalography involves recording and analysis of electrical signals generated by the brain), EP (the evoked potentials method involves analysis of a series of electrical signals generated in parts of the nervous system following stimulation of sense organs and peripheral nerves) and EMNG (electro-myo-neography is a method of measurement of electrical activity arising from muscle fibers and peripheral nerves)]. This method presents a valuable tool for assessment of functional state of peripheral nervous systems and muscles)), and neuroimaging (MRI of the brain). Thirty-seven out of 60 patients with NP-SLE (group I) were treated with a low dose of i.v. cyclophosphamide (200-400 mg per month). The average daily oral dose of prednisone in these patients was 20.5 mg. Group II consisted of 23 patients treated with pridnisone (mean dose 20.5 per day) only or with antimalarials. Patients in the first group showed a considerable clinical and electrophysiological improvement of cerebral function, while there was only a slight or no improvement in the second group. The difference between groups was statistically significant.