Objective:To assess the accuracy of BMI compared to directly measured dual-energy X-ray absorptiometry percent body fat (DEXA %BF) among a worker compensation population.Methods:The agreement between BMI and DEXA %BF was assessed by the Pearson correlation coefficient among 1394 evaluable patients over a 5-year period. Sensitivity and specificity were calculated to measure how well BMI can identify true obese and nonobese individuals.Results:Using at least 30kg/m2to identify obesity, BNI had a specificity of 0.658 and a sensitivity of 0.735. The correlation was better in females at 0.66, compared to males at 0.55, and weaker in older age groups at 0.42, as compared to the youngest age group at 0.59. Overall, 29.8% of the population was reclassified based on their DEXA %BF measures.Conclusions:In a 5-year cohort worker compensation population, BMI was an inaccurate measure of true obesity.