This study was designed to investigate the frequency of estrogen receptor (ER) gene polymorphism in Chinese patients with Parkinson's disease (PD). Polymerase chain reaction (PCR) method and restriction fragment length polymorphism (RFLP) were used to detect the ER gene polymorphisms in 158 PD patients and 146 healthy controls. In the PD and control groups, 'x' accounted for 83.5% and 80.8%, respectively (P>0.05). 'xx' was found in 77.2% of the PD group and in 69.9% of the control group (P>0.05). The frequency of 'p' in the PD and control group was 67.7% and 64.0%, respectively (P>0.05). 'pp' was 51.9% in the PD group and 43.8% in the control group (P>0.05). 'ppxx' was found in 49.4% of the PD and 43.0% of the control subjects (P>0.05). There was no significant difference in the 'x', 'xx', 'p', 'pp' or 'ppxx' between males and females within the PD or control groups. In conclusion, we found no significant differences in the genotype or allele frequencies between patients with Parkinson's disease and healthy subjects. These findings suggest that the estrogen receptor gene polymorphism may not play a key role in the pathogenesis PD in Chinese patients.