We analyzed the data obtained from neuropsychological evaluations of 12 neuro-Behcet Disease (NBD) patients who had been followed up for 35.6 +/- 23.7 months with successive neuropsychological testing by a comprehensive battery. Memory impairment, which seems to stem basically from a retrieval deficit, was the major finding in this series. The most severely affected memory process was delayed recall, being impaired in all of the patients in the verbal and/or visual modalities. This was followed closely by an impairment in the process of acquisition and storage. In addition to the memory impairment, a "clinical impression of personality change" toward either disinhibition or apathy was seen in 8 of the 12 patients. Attention deficit was of the third highest frequency and was present in 7 patients, followed by deficits of executive functions of frontal system which were present in 5. Other cognitive domains were rarely involved. Neuropsychological status deteriorated insidiously, regardless of the neurological attacks during the follow-up period in most of the patients. Furthermore, our observations also showed the presence of cognitive decline prior to detectable lesions on CT or MRI, emphasizing the need for neuropsychological testing in NBD patients. The late stages of the disease seem to be reflected in MRI as an enlargement of the third ventricle and atrophy of the upper brainstem, which could be compatible with memory loss. Our series, a rather selected group, suggests that NBD can be associated with a special pattern of cognitive deficit, especially memory loss and personality change. The designation of any specific neurobehavioral syndrome for NBD, however, awaits further study.