We studied long-term cognitive deficits in 20 patients with previously diagnosed Lyme borreliosis several years (average 51.6 months) after their acute phase of illness. Compared with an age- and education matched control group Lyme patients revealed deficits of verbal memory, mental flexibility, verbal associative functions and articulation, but performed adequately on tests of intellectual and problem solving skills, sustained attention, visuoconstructive abilities and mental speed. The late cognitive outcome was unrelated to disease variables from the acute stage of illness, but also to the interval elapsed since infection with B. burgdorferi. These and similar observations (Krupp et al. 1991) suggest that the so-called Lyme encephalopathy may be associated with a long-lasting neuropsychological deficit predominantly affecting mnestic functions.