Objective. To study the effects of motion sickness on posture equilibrium. Method. Dynamic posture was tested pre- and following motion sickness evoked by parallel swing. 17 healthy men were divided into motion sickness sensitive group (12) and motion sickness insensitive groups (5) according to their endurance times and the severeness of symptom. Result. The composite equilibrium score significantly decreased post-swing in all subjects. The composite equilibrium score, certain other equilibrium scores (SOT4, SOT5 and SOT6), the strategy scores (STRAT4 and STRAT6) and the sensory score (SEN3 and SEN5) significantly decreased in the sensitive group, but unchanged in the insensitive group post-swing. The equilibrium score (SOT2), and the sensory score (SEN1) pre-swing, the strategy score (STRAT3) of insensitive group is significantly higher than the sensitive group. Conclusion. Motion sickness can influence postural equilibrium. Postural instability and instability of strategy are related to the sensitiveness to motion sickness.