In this study, we investigated the characteristics of the reading materials in the elementary school science textbooks in order to obtain implications for the effective use of them. The reading materials in the elementary school science textbooks developed under the 7th and the 2007 revised National Science Curricula were analyzed. The criteria for classifying the reading materials were the type of theme, purpose, students` activity, the type of presentation, the type of images, the role of images, and readability. The results indicated that the reading materials in the 2007 revised science textbooks are more systematic than those in the 7th science textbooks in terms of their length and their distribution among energy, matter, life, and earth areas. It was also found that various types of reading materials are presented in the 2007 revised science textbooks covering new themes such as frontier science, job opportunity and career, and environment. In addition, the reading materials in the 2007 revised science textbooks introduce more visual images and the readability of them are also better than their counterpart. However, several limitations were still found to exist in the reading materials of the 2007 revised textbooks; most of them are non-inquiry and explanatory; most of the visual images are illustration and/or pictures. Educational implications are discussed.