This study investigates the effect of using the history of science in teaching geometrical optics on the motivation and conceptual understanding of first year university students. For this purpose, 54 students were randomly selected, then divided into two groups: the experimental group was taught by using history of science before traditional geometrical optics teaching, and the control group was taught by traditional method only. Data were collected using two instruments: Geometrical Optics Understanding Concept Test and Geometrical Optics Intrinsic Motivation Scale. The finding showed that before instruction, the students have important and prevalent misconceptions about vision, propagation of light and refraction. After teaching of geometrical optics, the study shows that using the history of science shows greater effect on intrinsic motivation and concept understanding. The results have some implications for teaching physics, especially when the traditional teaching is inevitable.