In today's mathematics education, teachers are expected to have an adequate understanding of mathematical literacy and to know how to incorporate mathematical literacy understanding into their instructional practices. Therefore, the purpose of this study was to investigate mathematics teachers' conceptions of mathematical literacy related to participation in a web-based learning environment about mathematical literacy and Programme for International Student Assessment (PISA). The case study method was used and the participants consisted of 20 mathematics teachers determined by the criterion sampling method. The data were collected by semi-structured interviews. In the data analysis process content analysis method was used. The results revealed that, the participants who participated the web-based PISA education conceptualized mathematical literacy in relation to the use of mathematical knowledge and skills to deal with real-life problems and associated supporting mathematical literacy with supporting development of problem solving skill. However, the others conceptualized mathematical literacy as having mathematical knowledge and skills to solve math problems and considered problem solving as a goal in supporting mathematical literacy.