Technical Abstract: Data from the National Health and Nutrition Examination Survey (NHANES) indicate that the prevalence of overweight and obesity continues to rise among Mexican Americans. Little is know about the dietary factors associated with this trend. Ethnic groups have different dietary patterns based on their geographical locations and cultural influences. We examined the dietary patterns of Mexican Americans and their association with total and central obesity. We hypothesized that Mexican American adults following a traditional diet would have a lower prevalence of obesity than those following a more typically American diet. Data from the NHANES 2001-2002 included 659 Mexican American adults, aged 18 y and older. Dietary patterns were defined by cluster analysis of food group variables, expressed as percentage contribution to total energy intake. Obesity was assessed by body mass index (BMI, kg/m^2) and central obesity by waist circumference. We defined four dietary patterns, each named for the food groups that were most predominant relative to the other clusters: poultry and alcohol, milk and baked products, traditional Mexican, and meat. Surprisingly, we did not identify a clear "healthy pattern" group in this population, as has been generally observed in other ethnic groups. Although the traditional Mexican diet contains relatively high intakes of legumes and of dietary fiber, it also was high in cholesterol. Contrary to our hypothesis, those consuming the traditional Mexican diet pattern had high values of BMI and waist circumference, which did not differ significantly from other groups. More details on possible changes within the traditional pattern associated with availability of foods, including use of fast food vs. home-prepared Mexican foods, are needed to better understand the observed association with obesity.