Hood development of internal structures in vehicles is an important alternative to minimize the injuries to pedestrians in case of a running over accident. In fact, according to Berg et al (2002), about 17% of head impacts occur on the hood. Moreover, according to Farooq and Schuster (2003), 62% of fatal injuries are caused by head trauma.This study focuses on evaluating the influence of free space between the hood and rigid components, considering cut out hood inner panel design, which is one of the geometries most commonly used by auto industries. The major advantage of this structure is its weight, leading, however, to small stiffness.Injuries to the head of a pedestrian is measured through a finite element model, in accordance with the European Committee for improvement in vehicle safety. There are several ways to measure the damage caused by the deceleration of the head. Here, the measure HIC (Head Injury Criteria), created by the NHTSA (National Highway Transport Safety Association) in 1971, is chosen, since it is still the most used and recommended method in the literature.Finally, the analyses of the numerical results lead to practical suggestions for auto industry.