The acetylator phenotype using sulphadimidine as a probe drug was studied in 20 idiopathic Parkinson's disease (IPD) patients and 21 control subjects. 10(50%) of the IPD patients belonged to the slow acetylator phenotype but this did not differ significantly from the proportion 7 (33%) of control subjects who were slow acetylators. The result does not suggest a role for acetylation in the aetiopathogenesis of IPD in Nigerian African.