The aim of the study was to compare the stability of the rider as well as the forces acting on the horse's back in the sitting trot and the rising trot. Ten sound horses were measured under the same experienced rider on a treadmill at trot. They were trained in 3 sessions to get used to the treadmill and were wearing a fitting dressage saddle without saddle pad. For collecting the kinetic data a pressure mat under the saddle was used. The rider performed the 2 different seating positions; sitting trot and rising trot 20 s each. Right forelimb motion was used to synchronise the pressure data with the stride cycles. For determination of the rider's stability, the movement of the centre of pressure (COP) along the transverse (x) and longitudinal (y) axis was calculated. To evaluate the load on the horse's back, the force was estimated. The force and the stability were evaluated using the ANOVA for repeated measures (p < 0.05) in SPSS 14.0. Significant differences could be shown between the seating positions for the maximum deviation along the y-axis. The stability of the rider in y-direction was significantly higher in the rising trot than in the sitting trot. In x-direction, there was no significant difference between the 2 positions. The amplitude of force was also significantly higher in sitting trot (1781 N) compared to rising trot (1476 N). The rising trot was found to be more stable and less stressful for the horseback when compared to the sitting trot.