A 60-year old man developed a subacute psychoorganic syndrome over four weeks. CCT was normal, except a slight atrophy of the cerebellar superior vermiform process. In the CSF we found 1696/3 cells, suggesting a lesion of the hemato-encephalic barrier, an autochthonous IgG production and an increased specific antibody-titre (10.3) for Borrelia burgdorferi. Based on these data a
Lyme-Neuroborreliosis being diagnosed. Treatment with Cefotaxim and Gentamycin was successful, a complete remission of the psychopathological symptoms had been obtained. This case is an uncommon manifestation of a Borrelia-burgdorferi-infection of the CNS with psychopathological symptoms but no neurological deficit. We conclude that an affection of the CNS with Borrelia burgdorferi must always be taken into consideration in patients presenting a subacute psychoorganic syndrome of unknown etiology.