The purpose of this study was to investigate the impact of body mass index (BMI) on the outcomes of IVF/ICSI treatment cycles in Chinese patients with polycystic ovary syndrome (PCOS). Women with PCOS (n = 128) and tubal factor (n = 128) underwent a conventional long GnRH agonist suppressive protocol. Women with PCOS had significantly more oocytes retrieved (P < 0.05) and available embryos (P < 0.05), as compared to patients with tubal infertility. No significant differences were observed in clinical pregnancy rate, miscarriage rate and live birth rate between two groups. Patients were further divided into two subgroups. In total, 49 patients in PCOS group and 19 patients in tubal factor group were overweight or obese (BMI >= 24 kg/m(2)). Lean women (BMI < 24 kg/m(2)) with PCOS showed higher clinical pregnancy rate (P < 0.05). Live birth rate and miscarriage rate were also higher in lean PCOS women, but the differences were not significant. Similar clinical outcomes of IVF/ICSI success were achieved between two subgroups in tubal factor patients. In conclusion, lean PCOS patients obtained higher clinical pregnancy rate compared with overweight/obese PCOS patients in Chinese populations.