With the early captures in the reign of the early caliphates of Islam, the Arab Muslims conquered a number of areas which the ancient civilizations, including Mesopotamia, Egypt and India, lived before. From the beginning Non-Muslims who were in this conquered area made important contributions to the Muslims. Among them, Christians were the most important ones. They served the caliphs in medicine science. Later, they made further progress with their translations. They gained at theoretical medicine science. They drew attention with other services. In this paper, I will discuss mainly, the contributions of the Christian doctors to the Islamic society in the Abbasid times