Low speed rear impacts were simulated using finite element (FE) models. THUMS Version 4 AM50 and AF50 Occupant Models were used for representing average‐sized male and female occupants, respectively. Capsule models were introduced into the cervical joints to calculate tissue strain for estimating the neck load. Rear impact simulations were conducted to investigate the gender difference of head and cervical spine kinematics. The first series of simulations compared the head and cervical spine kinematics of the male and female occupants without muscle tone, assuming the same backset. The next series was performed with muscle tone in the neck. The other series was conducted to investigate the effect of backset for the female occupant. Three acceleration pulses were used for the first series. The simulation results indicated that the greater neck extension of the female occupant was due primarily to the less stiff neck. The muscular force worked both raising and lowering the joint capsule strain and resulted in bridging the gender difference. The shortest backset did not necessarily give the lowest joint capsule strain. The relative displacement between the head and torso was given by the head and torso displacement pushing against the head restraint and seatback.