This study directly compared two different perturbation profiles, using repeated measures, to evaluate vertical and horizontal head accelerations during whiplash-like perturbations. We observed that the magnitude of the vertical head accelerations depended on the specific perturbation parameters; the horizontal and vertical acceleration magnitudes were not significantly different in the mild perturbation, but the horizontal head accelerations were significantly larger than the vertical accelerations during the moderate perturbations. These findings illustrate that human subjects have different responses to whiplash-like perturbations depending on the specific acceleration profile parameters, including peak acceleration. This finding is in contrast to one study that found that the vertical and horizontal head accelerations were highly correlated for seven different perturbation profiles (Siegmund et al., 2004), but somewhat supported by a different study that observed differences in the magnitude of the vertical head acceleration between female and male subjects (Hernandez et al., 2005). Our finding supports a recent in vitro experiment that observed that the crash pulse shape influences the peak loading and the injury tolerance levels of the neck in simulated low-speed side-collisions (Kettler et al., 2006).