In 30 subjects (16 men and 14 women) stabilometry was used to investigate the stability of posture with closed eyes and different positions of the head (backward, forward, right and left turn). Cervical spine mobility of the subjects studied was determined by vertebrogenic examination. The maximum backward extension of the head was found to reduce most markedly posture stability. Correlation analysis revealed a relationship between the functional state of the cervical spine and the degree of posture stability impairment induced by backward extension of the head, with the impairment being more pronounced in the forward-backward direction. The obtained results show that changes in the quality of proprioceptive information from the cervical spine region are also involved in determining the stability level of upright posture. The findings imply that posture with backward extension of the head can be used as a loading test for detecting ataxia of cervical origin.