The existence of Islamic law in the history and politics is an inseparable part of the Moslems' life, including, in this case, Indonesian Moslem society. In Indonesia, before the arrival of the Dutch, the Islamic laws had existed, becoming the laws which were applied by Islamic empires spreading all over Indonesia. This condition had changed since the Dutch arrived and had colonized Indonesia for 350 years. Even After earning its independence, the development of Islamic laws implementation moves slowly because the applied law paradigm has still used the Dutch laws which still exist in Indonesia. However, the development of Islamic laws gradually took its momentum in 1990s by the introduction to the profit sharing system in Indonesian banking which is apparently a part of Shari'ah banking. This paper is intended to elaborate the Islamic laws history and development in Indonesia and described how Islamic laws have then become in integral part of Indonesian national laws system. Besides, this paper discusses the appearing problems in the implementation of Islamic laws in Indonesia and suggests some feasible solutions in integrating the Islamic laws into the Indonesian national legal systems.Key words: Integration, Islamic Laws, National Legal System.