Abstract Governments, are not successful in implementation of many policies. Various challenges, obstacles and constraints may occur and hamper the policy implementation; but when a policy fails in implementation, only the implementators are blamed; while policy-makers have a major role in the (success and) failure of a policy, too. In fact, disrespect to rationality in policy formulation can lead the policy process to failure in implementation. In this study, according to Ignace Snallen (2002), the concepts of rationality consists of legal, economical, political and professional dimensions. The hypothesis of this research is that “rationality of the policies formulated in the 7th Islamic Consultative Assembly of Iran” differs to “the optimum/ideal rationality that, leads us to a successful implementation”. The necessary data were gathered from the experts by questionnaire, and analyzed by statistics tests. Data analyses confirmed the research hypothesis. It is concluded that disregard to the desirable composition of rationalities has led the to unsuccessful implementations of policies processes.