Biao and ben are contrasting concepts used to indicate the primary and secondary relationships of contradictory sides in various kinds of diseases and syndromes. For example, body resistance (or anti-pathogenic factors) are considered ben (root) while pathogenic factors are biao (branch); etiology is ben, symptoms is biao; primary disease in ben, secondary disease is biao; pathological changes of internal organs are ben, body surface is biao, etc.

The principle of biao and ben is used in traditional Chinese medicine to treat the symptoms at the acute stage and to treat the root of disease at the chronic stage. If biao and ben have the same severity, treatment should then be applies to both ben (root cause) and biao (symptoms).