The aim of this study is to reveal the perspectives of secondary school mathematics teachers about the use of materials in mathematics teaching. For this purpose, the teachers' use of materials, the materials they have used, and their views on the role of using materials were analysed. In this context, the research was conducted with case study, one of the qualitative research designs. In accordance with the purpose of the research, easily accessible case sampling method was used to form the study group. The data of the study were collected from eight secondary school mathematics teachers working in different schools on a voluntary basis with a semi-structured interview form consisting of three open-ended questions about the use of materials in mathematics teaching. The interviews were audio recorded and the dialogues were transcribed. The data obtained were analysed by content analysis method. As a result of the study, it was determined that teachers' perspectives on the use of materials were built on four themes: the role of purpose of use, the role of effect on teaching, the role of effect on students and the materials used. Regarding the purpose of using the material, it was determined that most of the teachers emphasised the role of attracting attention to the lesson, the role of concretisation as the effect on teaching, and the role of facilitating understanding and remembering as the effect on students. Although the teachers stated that the use of materials had a positive effect, it was concluded that their use in the application dimension was at a low level. Another striking result of the study was that the concrete materials that some teachers stated that they used were actually course materials. When the focus was on what they used as materials, it was determined that all of the examples given were concrete materials actively used in the geometry learning domain. In addition, only one of the eight teachers participating in the study mentioned virtual learning objects (manipulatives) other than concrete materials as materials.