It appears that certain factors, such as the movements of the leading forelimb and head of the horse, and the existence of the rider, influence a horse's jumping performance during show jumping. The purpose of the present study was to investigate the fundamental timing control of the horse's movement immediately before jumping and to consider the relationships between these factors. Video recordings (60 frames/s) were made using four 8-mm video cameras from 4 angles around a 100-cm-high fence. The 3-D coordinates were calculated using the direct linear transformation (DLT) method. The movements of the horse with and without the rider were compared and analyzed during a few strides before jumping. The subjects were two sound horses and two skilled student riders. The results are summarized as follows: 1) Upward movement of the horse's head immediately before jumping was still evident after the forelimbs had left the ground. This situation was different from that reported for galloping horses (Amano and Ishii, 1992). 2) Immediately before jumping, the horse took a position with a shorter stride between the forelimbs. This shorter stride probably contributes to the upward movement of the horse's head mentioned in 1), and to the more forward landing of the hindlimb before jumping. 3) In relation to this short stride of the forelimb before jumping, the horse increased the landing angle of the leading forelimb and decreased the take-off angle to change its forward velocity to a more upward velocity. 4) There was no significant difference between the ridden and non-ridden horses in the timing control of the vertical movement of the horse's head and the pre-jump velocity. This may be due to the ridden horse's control of its own movement by decreasing the take-off angle of the leading forelimb in order to jump the fence. However, more cases should be examined to clarify and quantify these influences.