Objective: Epidemiologic analyses indicate a lack of association between BMI (kg/m2) and mortality among Hispanic adults. Because BMI provides only a surrogate for the real variable of interest, adiposity, this study evaluated associations between measures of body composition and mortality. Methods: Using data from US-residing Mexican Americans in the National Health and Nutrition Examination Survey (NHANES) III (n = 4,480) and NHANES 1999-2010 (n = 5,849), the association between seven measures of body composition measured via anthropometry and bio-electrical impedance analysis (i.e., waist circumference, waist-to-height ratios [WHtR], skinfolds, lean mass, fat mass, percent body fat, and BMI) and all-cause and cardiovascular and diabetes mortality were examined. Additional analyses were stratified by gender. Results: Waist circumference (hazard ratio [HR]: 1.04, 95% CI: 1.01-1.07) and WHtR (HR: 1.08, 95% CI: 1.03-1.14) were weakly associated with an increased all-cause mortality, while WHtR was associated with an increased risk of diabetes-related death (HR: 1.26, 95% CI: 1.07-1.49). In gender-stratified analyses, there was an increased risk of mortality in females who had increases in WHtR and waist circumference for all-cause mortality and cardiovascular deaths. Conclusions: Waist circumference and WHtR were associated with increased risk of all-cause and diabetes-related mortality in US-residing Mexican American adults.