Adiponectin levels were measured in African American and Caucasian women of varying body mass index (BMI). Plasma adiponectin levels were compared and the relationship between adiponectin and insulin sensitivity was assessed. Adiponectin levels were similar in the Caucasian obese (7.0 +/- 0.8 microg/mL), African American obese (7.3 +/- 3.5 microg/mL), and African American non-obese women (7.1 +/- 1.2 microg/mL), but were significantly higher in Caucasian non-obese women (12.2 +/- 1.4 microg/mL). Correlational analyses demonstrated that BMI, insulin, and homeostasis model assessment (HOMA) correlated significantly with adiponectin levels in only the Caucasian women. These results provide support for the notion that what applies to other ethnic populations might not apply to the African American population, and that the association between adiponectin and insulin sensitivity needs to be clarified in the African American population.