Purpose To evaluate the correlation between anti-mülle-rian hormone (AMH) and body mass index (BMI) in patients with and without polycystic ovarian syndrome (PCOS). Methods Serum AMH levels of 332 women in their reproductive period and below 45 years of age who were admitted to our reproductive endocrinology clinic with infertility were investigated in a cross-sectional study. Patients were divided into two groups as BMI under and equal or over 25 kg/m 2 . Both groups were divided into two subgroups as PCOS and non-PCOS. AMH levels of patients were analyzed for each group. Results Mean AMH values of BMI \25 and C25 kg/m 2 groups were 3.87 ± 2.95 and 3.58 ± 2.93 ng/mL, respectively (P [ 0.05) in all patients. Means of AMH were not significantly different in BMI quartiles (r = -0.008401, P = 0.96). Among 107 patients with PCOS, means of AMH were 6.85 ± 2.95 ng/mL in 56 patients with BMI \25 kg/m 2 and 6.66 ± 3.18 ng/mL in 51 patients with BMI C25 kg/m 2 (P [ 0.05). In the group of 225 non-PCOS patients, means of AMH were 2.27 ± 1.12 ng/mL in 104 patients with BMI\25 kg/m 2 and 2.28 ± 1.49 ng/mL in 121 patients with BMI C25 kg/m 2 (P [ 0.05). Conclusions Body mass index does not seem to have an effect on serum AMH levels in reproductive age women both with and without PCOS.