The objective of the study was to document the thoracic deformation contours in a simulated frontal impact. Unembalmed human cadavers and the Hybrid III anthropomorphic manikins were tested. Data from the newly developed External Peripheral Instrument for Deformation Measurement (EPIDM) was used to derive deformation patterns at upper and lower thoracic levels. Deceleration sled tests were conducted on three-point belt restrained surrogates positioned in the driver's seat (no steering assembly) using a horizontal impact test sled at velocities of approximately 14.0 m/s. Lap and shoulder belt forces were recorded with seat belt transducers. The experimental protocol included a Hybrid III manikin experiment followed by the human cadaver test. Both surrogates were studied under similar input and instrumentation conditions, and identical data acquisition and analysis procedures were used.All six testedcadavers demonstrated multiple bilateral rib fractures. In addition, clavicle and sternum fractures were found. In one case, lung and liver lacerations occurred in the region of rib fracture. The location, magnitude, and time of occurrence of the maximum chest deflection demonstrated differences between the two surrogates; the patterns of the thoracic deformation contour were also different. Regions of high local curvature/deformation were identified in the human cadaver tissue. Maximum chest deflections ranged from 2.7 to 13.0 cm at the upper level (ribs 2 - 4) and 2.5 to 12.3 cm at the lower level (ribs 6 - 8) in the cadaver. The corresponding chest deflections in the Hybrid III manikin ranged from 3.3 to 6.7 cm and 2.9 to 5.7 cm at the upper and lower levels, respectively. The deflections recordedusing the internal potentiometerranged from 2.7 to 4.0 cm in the manikin. It can be concluded that the human cadavers in these tests exhibit greater regional differences and are more compliant in their thoracic deformation characteristics than the Hybrid III anthropomorphic manikin.