To investigate the correlation of 4G and 5G genetypes distribution of plasminogen activator inhibitor-1 (PAI-1) gene polymorphism in its promoter region with polycystic ovary syndrome (PCOS). In 101 Chinese PCOS patients and 42 women as control, 4G and 5G polymorphisms of PAI-1 gene were detected with PCR-restriction fragment length polymorphism (RFLP). Pregnant history, body mass index (BMI), waist-hip ratio (WHR) were collected and Homastasis Model Assessment score for insulin resistant (Homa-IR) and insulin sensitive index (ISI) in PCOS groups were calculated. The distributions of PAI-1 gene polymorphisms 4G type (4G/4G genetype) and 5G type (5G/5G, 4G/5G genetype) were different between the PCOS group and the control. The PCOS group had higher 4G type 57% (58/101) distribution than that of the control group 38% (16/42); 5G type is vise verse (P < 0.05). PCOS patients were divided into obese and non-obese sub-groups according to BMI. There were significant lower Homa-IR and higher ISI in non-obese subgroup