Five patients with idiopathic PD were followed by neuropsychological tests after brain fetal neuronal transplantation. The following tests were used in order to assess memory as well as visuospatial and frontal functions: MMSE, Mattis Scale, Wisconsin Card Sorting Test, Stroop task, word fluency tasks, 15-objects test, WAIS-R (Digit span, Arithmetic, Block design, Pictures completion, Pictures arrangement), learning of 15 words of Rey, WMS-R (Logical memory) and Visual memory of L. Israël. The same tests were performed before, then one year following the transplantation. Pooled data did not show any significant difference between pre and post-operative tests. Individual results varied among patients: 2 remained unchanged, 1 had a pathological deterioration which increased after one year, 1 had some frontal symptoms whereas the last patient improved. Our data confirm that this surgical procedure do not induce permanent neuropsychological deficits, but do not indicate at the present time any clear effect of dopamine reinnervation on cognitive functions.