Modern forms of transportation can impose high levels of vibration upon their occupants. If one is concerned with the welfare and comfort of the passengers, or the ability of the pilots or drivers to perform their respective tasks in such an environment, then clearly one needs to be able to define the vibration levels experienced by such people. This definition must not only quantify the input levels but also include the levels measured at that part of the human body which will be most affected by the vibration. This thesis therefore covers work aimed at determining the frequency response of the human body under vibration conditions and presents amplitude ratio and phase angle plots of head, and shoulder, accelerations/seat acceleration against frequency for various postures and limb positions.