The chronic degenerative disorders of the rachis represent a growing topic in medical and social fields. In fact the problem of back-pain involves an ever increasing percentage of population, and various epidemiological studies show how spread is the phenomenon in the industrial countries. In this context a main role is played by the sitting posture. In fact it is well known that, in industrialised countries, people spend during their life course the majority of their time in everyday activity by being seated either at school or at work or at home etc.. It is evident how important is to define and to study the characteristics of the “correct sitting posture”. The aim of this study is to perform a statistical biomechanical analysis on a sample population of both the standing and the sitting posture (with standard and special chair: the VARIABLE balans^® model designed by STOKKE) by using the AUSCAN System and a new statistical approach.