This study examined the sensitivity and specificity of current methods for classifying morbid obesity in females. Results suggest that current methods for classifying morbid obesity (greater than or equal to 45.5 kg over ideal weight or BMI greater than or equal to 45) do not provide acceptable specificity and sensitivity, respectively. We suggest that additional measurements such as total body fatness determined by hydrodensitometry be used to classify morbid obesity and determine eligibility for aggressive therapeutic interventions for weight loss.