Many studies have investigated teachers’ curriculum use in order to explain student achievement and opportunities to learn mathematics (Brown, 2002; Lloyd, Remillard, & Herbel-Eisenmann, 2009; Stein, Remillard, & Smith, 2007). However, little has been known about how teachers understand the roles of non-textual elements (e.g., pictures, illustrations, graphs, and mathematical figures) for effective teaching and learning. By analyzing qualitative data from 10 South Korean and 11 U.S. secondary mathematics teachers, this study explores what aspects of non-textual elements teachers consider important for teaching and learning and how teachers understand the roles of non-textual elements in their instruction. The results from this study show that both South Korean and U.S. teachers regard accuracy, aesthetics, connectivity, and contextuality as important aspects of non-textual elements for effective teaching and learning. However, their emphases on, and usages of, non-textual elements in their classrooms were largely different between South Korea and the United States. In particular, South Korean teachers tended to focus on mathematical connectivity and mathematical accuracy (with regard to the definition of a concept), emphasizing the nature of mathematics as a logical and abstract subject. U.S. teachers, however, put more emphasis on contextuality and accuracy (with regard to mathematical application and usefulness). It is also notable that both South Korean and U.S. teachers preferred simplicity to variety, despite many studies that have emphasized the importance of various mathematical experiences in student learning. Teachers' lack of understanding of the importance of variety may lead to students’ misconceptions due to the fallacy of "one-case concreteness" (Presmeg, 1997). Comparing South Korean and U.S. teachers’ perception of non-textual elements in mathematics textbooks, this study provides useful information atextbwhat criteria teachers have in selecting non-textual elements for their instruction as well as how to improve the quality of non-textual elements in mathematics textbooks for effective teaching and learning. This study also calls for further investigations of non-textual elements as well as teacher education and professional development prog nms that give attention to the importance of non-textual elements in mathematics education.