The international humanitarian law is certainly one of the most interesting topic of international law. International humanitarian law (IHL) which can briefly be defined as the set of rules applicable in armed conflict, has been longtime criticised as bearing contradictions in itself. It was argued that in a legal system where the recourse to use of force is forbidden, it was contradictory to make rules aiming at regulating this use of force. But taking into account the terrible impact of armed conflict especially on civilians, it becomes meaningless to question this contradiction. The aim of this study is to analyse the fundamental principles of distinction between civilians and combatants in IHL and to observe its application in the recent Iraqi conflict. It should be kept in mind that this is a study of IHL, thus the reasons behind the armed conflict as well as the legitimacy of the recourse to use of force against Iraq by coalition forces do not fail within the scope of this work. The IHL applies to all forms of armed conflict irrespective of the legitimacy of the latter.