Abstract: Objective To study the clinical relationship between peripheral blood leukocytes, obesity in patients with polycystic ovary syndrome(PCOS).
Methods 126 PCOS patients were retrospectively analyzed. According to body mass index(BMI), the patients were divided into normal weight group(n=69), overweight group(n=57). Statistical analysis of general clinical data, testing including levels of sex hormones, glucose and lipid metabolism factors and inflammatory factors. 
Results Compared with normal weight group, the levels of body weight, BMI, waist circumference（WC）, hip circumference（HC）, WHR, fasting plasma glucose, fasting insulin, HOMA-IR, triglyceride, cholesterol total, low density lipoprotein, white blood cell, lymphocyte, monocyte and neutrophil are higher in overweight group, while the levels of luteinizing hormone（LH）, follicle stimulating hormone（FSH）, LH/FSH,sex hormone binding globulin, high density lipoprotein, apolipoprotein A and apolipoprotein B decreased significantly(P＜0.05). 
Conclusion The pathogenesis of PCOS is not clear, the chronic low-grade inflammation plays a key role in the pathogenesis of PCOS. The severity of chronic low-grade inflammation in PCOS is closely related to overweight or obesity. 

Key words: polycystic ovary syndrome, obesity, chronic inflammation