Iranians have had a large share in the progress of science, particularly intellectual knowledge, medicine, pharmacy and paramedical era before and after the emergence of Islam. Jundi Shapur University of Medical Sciences in Ahvaz and "Ryvardshyr” (now Bushehr) at that time suggests that, in Sassanid era, Iranians paid special attention to develop the intellectual sciences. Iranians’ medical works have been considered among the most important sources in the Islamic world. The main factors of the Iranians’ influence in the development and publication of intellectual sciences during the Islamic civilization can be summarized as follows:1. Iranians’ domination in science and literature and their power in the Abbasid government2. Iranian religious campaigns and the Abbasid rulers’ concerns about intellectual sciences and philosophy3. Iranians’ familiarity with various kinds of human knowledge, including medicine, mathematics, and translation techniques.