The objective of this analysis was to determine the prevalence of obesity and its association with selected medical conditions in a non-institutionalized elderly Mexican-American population. Data employed are from a representative sample of 3050 elderly Mexican Americans from the five Southwestern states: Texas, California, Colorado, New Mexico, and Arizona. Complete Body Mass Index (BMI) data were available for 2769 individuals. The in-home survey obtained socio-demographic data, anthropometric measurements, including height and weight, blood pressure readings, self-reported health conditions and depressive symptomatology. It was found that 23% of men and 35% of women were obese (BMI > or =30 kg/m2). Using a weighted logistic regression model, a BMI of > or =26 kg/m2 was associated with a significantly higher risk of diabetes; a BMI of > or =30 kg/m2 was significantly associated with arthritis and measured hypertension and a BMI<22 kg/m2 was associated with a higher likelihood of self-reported cancer. In addition, the prevalence of obesity was found to be much higher in this elderly Mexican-American population than in the general population.