Drop tests have been simulated using Finite Element (FE) head and multi-mass headform models to investigate differences in the dynamic response of real heads and dummy headforms. Maximum differences in the peak resultant linear and rotational skull accelerations predicted by deformable and rigid human head models were 75 g (30 %) and 6219 rad.s-2 (115 %). Equivalent differences in the predictions from deformable and rigid multi-mass headform models were 8 g (3 %) and 528 rad.s-2 (4 %) respectively. In contrast to the other head model structures the deformable head model predicted a reversal in skull rotational motion under one specific impact condition.