A comparison of the NHTSA advanced dummy and the Hybrid III is presented in this paper based on their performance in twenty four frontal impact sled tests. Various time histories pertaining to accelerations, angular velocities, deflections and forces have been compared between the two dummies in light of their design differences. This has lead to some understanding about the differences and similarities between the NHTSA advanced dummy and the Hybrid III.In general, the chest as well as the head motion in the NHTSA advanced dummy are greater. The lumbar moments in the NHTSA advanced dummy are lower than that in the Hybrid III. The upper and lower spine segments in the NHTSA advanced dummy, generally rotate more than the spine of the Hybrid III. Although in the sled tests, differences in the pelvic motion, the femur loads, the tibia loads, and the neck loads have also been observed between the NHTSA advanced dummy and the Hybrid III, very general conclusions can not be drawn about them because of their dependence on the restraint modes.It appears that the new thoracic system in the NHTSA advanced dummy is largely responsible for the observed differences with the Hybrid III dummy. However, the differences in the shoulder and the lumbar also contribute to the differences in the response of the two dummies.