The most important tool used in testing methods for evaluating the performance of seat-systems in rear-end impacts is a biofidelic crash test dummy. It has been reported that there are differences in response between two kinds of such dummies, BioRID P3 and Hybrid III, in rear-end impacts at Δ V=9.2 km/h. The objective of this study is to compare the responses of these two types of dummies, at moderate speeds with HYGE sled tests (Δ V=15 km/h, 25 km/h). At Δ V=25 km/h or less, the BioRID and HYIII dummies showed clear differences in their response to a rear-end collision, and the BioRID showed higher biofidelity than the HyIII in this condition.