The purpose of this study was to characterize the biodynamic response of a supine human during the loading and unloading procedures on a MEDEVAC aircraft. An instrumented manikin with accelerometers and gyroscopic sensors replicated the human biodynamic response to vibration and mechanical shock. Two platforms, the Basic Medical Interior (BMI) on the HH-60 and the Interim MEDEVAC Mission Support System (IMMSS) on the UH-60 were used for testing. Other parameters were varied throughout the study including loading height, loading direction (head first versus feet first), and litter pole sensor placement (inboard versus outboard). Results showed that loading the litter imparted significantly more vibrational exposure to the manikin than walking the litter. There were no significant differences in vibratory exposure between the two MEDEVAC platforms. No significant difference was also observed when comparing loading the manikin head first versus feet first, or when comparing loading at the top height versus the bottom height within the platforms. This study indicates that litter loading and unloading procedures result in statistically significant exposure to vibratory motions and may result in exacerbating casualty injury. Aircraft design and litter bearer training may help reduce some exposure to these motions.