The motor and neuropsychological abnormalities in eight Greek patients with Parkinson's disease (PD) carrying the α-synuclein gene mutation (G209A) were studied. These patients (five men, three women) belonged to six different families. Their symptoms started between 32–50 years of age (mean ± SD, 39.7 ± 7.6 years) and they had a mean disease duration of 5.4 ± 2.1 years (range, 2–9 years) at the time of examination. Rigidity and bradykinesia predominated both at disease onset as well as in the later stages and rest tremor was relatively uncommon. Neuropsychological assessment showed that one patient was mildly demented while another had impairment in memory, visuoconstructive abilities, and executive function. Depression was present in only one patient. Our findings indicate that genetic forms of parkinsonism share common motor and cognitive characteristics with sporadic PD but raise the possibility that greater cognitive impairment and the relative rarity of tremor may be distinctive features worthy of further investigation. © 2001 Movement Disorder Society.