In recent years, there has been much discussion of the influence of classical Arabic science on the Western scientific tradition. Yet these achievements have been variously ignored, overlooked or occasionally overstressed. This lecture discusses the impact that scholars from the Islamic world have made in the fields of medicine, astronomy, optics, geography, mechanics and many other disciplines. What role did the Arabic world have in the history of science? And how did Baghdad, Cairo and Islamic Spain preserve and expand the scientific tradition?