Studies of cognitive functioning in patients with systemic lupus erythematosus (SLE) have found deficits even in patients without other evidence of neurologic involvement. The present study used scores on the 11 items of the Mini-Mental State Exam (MMSE) to classify the cognitive impairment of 93 SLE patients as suggestive of “cortical” or “subcortical” dysfunction using a validated statistical algorithm. Ninety-five percent of patients were categorized as having “subcortical” deficits, and 5% were categorized as having “cortical” deficits. When the analysis was limited to only those with total MMSE scores ≤ 24, 81% were classified as “subcortical” and 19% as “cortical.” These results suggest that SLE patients can have psychomotor and mental tracking deficits of a type seen in patients with subcortical brain disease, even in the absence of gross neurologic involvement. (JINS, 2000, 6, 821–825.)