Systemic lupus erythematosus (SLE) is an autoimmune-mediated collagen disease that results in multiorgan failure. It is the collagen disease most frequently associated with neuropsychiatric symptoms, which have been hypothesized to stem from certain types of cognitive dysfunction. Subjects were 21 patients with SLE (one man, 20 women; aged 16-55 years; mean age, 35.1+/-10.7 years) who were undergoing treatment in the rheumatology unit of a general hospital, and 17 healthy control subjects matched to the patient group with respect to age and gender (two men, 15 women; mean age, 35.9+/-6.3 years). They were administered various tests of cognitive function including verbal reasoning, non-verbal reasoning, verbal memory, non-verbal memory, attention and mental flexibility, psychomotor speed and frontal lobe function. In addition, the SLE patients were tested for antiphospholipid antibodies. The SLE patients performed worse than the control group on immediate, delayed and interference of the Rey verbal test and paired associate tests of Wechsler Memory Scale, and their reaction time was slower in Trail A and Trail B tests. Moreover, these findings were more pronounced in the group with major neuropsychiatric symptoms. However, no relationship was apparent between these deficits in cognitive function and the presence or absence of antiphospholipid antibodies. The results suggest that verbal memory and psychomotor speed underlie the neuropsychiatric symptoms seen in SLE patients.