Objective: The aim of this study was to determine an optimal waist circumference (WC) cutoff value for defining the metabolic syndrome (METS) in postmenopausal Latin American women. Methods: A total of 3,965 postmenopausal women (age, 45-64 y), with self-reported good health, attending routine consultation at 12 gynecological centers in major Latin American cities were included in this cross-sectional study. Modified guidelines of the US National Cholesterol Education Program, Adult Treatment Panel III were used to assess METS risk factors. Receiver operator characteristic curve analysis was used to obtain an optimal WC cutoff value best predicting at least two other METS components. Optimal cutoff values were calculated by plotting the true-positive rate (sensitivity) against the false-positive rate (1-specificity). In addition, total accuracy, distance to receiver operator characteristic curve, and the Youden Index were calculated. Results: Of the participants, 51.6% (n = 2,047) were identified as having two or more nonadipose METS risk components (excluding a positive WC component). These women were older, had more years since menopause onset, used hormone therapy less frequently, and had higher body mass indices than women with fewer metabolic risk factors. The optimal WC cutoff value best predicting at least two other METS components was determined to be 88 cm, equal to that defined by the Adult Treatment Panel III. Conclusions: A WC cutoff value of 88 cm is optimal for defining METS in this postmenopausal Latin American series. © 2012 by The North American Menopause Society.