The authors conducted a case-control study of Parkinson's disease patients with and without visual hallucinations to investigate associations of the polymorphisms of the dopamine receptors D2 32806 C>T (Taq1A), D3 Ser9Gly and Msp1, D5 978T>C and dopamine transporter 3'-UTR 40 bp VNTR with visual hallucinations in Parkinson's disease.