Improvised explosive devices (IEDs) deliver a high energy blast to the underbody of military vehicles, consequently exposing modern Warfighters to considerable risk during ground transport. Biomechanical data are required to determine if a separate, operationally relevant anthropomorphic test device (ATD) suited for the assessment of risk associated with the female Warfighter should be developed, or if injury prediction outputs from the male ATD can be mapped to females. The objective of this study is to determine the differences between female and male impact and damage response in the under-body blast (UBB) environment. This study was conducted using the Accelerative Loading Fixture (ALF), which generates floor and seat loading conditions representative of UBB. Sixteen post-mortem human surrogates (PMHS) were tested, using two floor conditions. The PMHS tested include 50th percentile males, and 5th and 75th percentile females. The data obtained include the generalized kinematics of the distal tibia and femur, sagittal perspective planar segment motion, and PMHS lower extremity damage. The female and male tibia vertical acceleration and speed responses are similar in shape. All females attain greater speed earlier in the event. The 5 th percentile female femurs attain greater acceleration earlier in the event during the lower-energy floor condition, while the 75th percentile female femurs attain greater acceleration during the higher-energy floor condition. The femur acceleration response of the female is notably shorter in duration, but similar in shape to the male response. The female lower extremities initially rotate in the sagittal plane at a higher rate than those of the males. Damage to the lower extremities was sustained during the higher-energy floor condition. Differences in damage response between sexes and percentiles are likely due to a combination of sex-related tolerance, anatomy, and mass phenomena. The results suggest that both the kinematics and damage response of female PMHS are markedly different than those of male PMHS.