There is increasing evidence that adiponectin has a critical role in the development of breast cancer, but factors that influence adiponectin concentrations have not been well studied. We conducted a cross-sectional study among Asian-American controls who participated in a population-based case-control study of breast cancer. Participants were interviewed in-person and donated a blood specimen. Using multivariate models, we investigated the relationships between serum adiponectin concentrations and lifestyle factors (including adiposity and dietary factors) and serum sex-hormones and growth factors among postmenopausal women who were nonhormone-users at blood draw (n = 196). Adiponectin concentrations were significantly positively associated with green tea intake (P trend = 0.03); levels were 31% higher among those who drank green tea 4 or more times per wk (14.5 ± 1.10 μg/mL) compared with nongreen-tea-drinkers (11.0 ± 1.09 μg/mL); this association remained after adjustment for body mass index (BMI) and waist/hip ratio (WHR), both of which were significantly and inversely associated with adiponectin. Adiponectin concentrations were positively associated with sex-hormone-binding globulin (P trend < 0.0001) and the ratios of total testosterone (T)/total estradiol (E2) (P trend <0.004) after adjustment for BMI and WHR. Confirmation of our findings on green tea and adiponectin is needed.