An environment shaped by students' cultural and everyday experiences contributes to meaningful learning. In this way, the knowledge learned is internalized by students as it bears traces of culture. In this context, it is thought that including cultural differences in the materials developed in the education and training process will increase the awareness of prospective mathematics teachers about the relationship between mathematics and culture. In this study, it was aimed to reveal the thoughts of prospective mathematics teachers about the process of preparing ethnomathematics-based materials and their possible effects on students. The sample of the study consisted of 25 prospective mathematics teachers enrolled in the Department of Mathematics Education at a state university in the Central Anatolia region who had taken and successfully completed the ‘Material Design in Mathematics Teaching’ course. The research is a qualitative study using case study design. A semi-structured interview form consisting of 7 questions was applied to the prospective teachers in order to determine their thoughts about the process of preparing ethnomathematics-based materials and their possible effects on students. The answers given by the prospective mathematics teachers to the open-ended questions were analyzed using content analysis, one of the qualitative analysis methods. As a result of the research, it was seen that prospective mathematics teachers mostly used architectural structures such as mosques, tombs, water wells and cultural elements such as carpets-rugs, tile patterns and marbling art while preparing ethnomathematics-based materials. It was determined that prospective teachers had difficulties in preparing ethnomathematics-based materials at points such as technical works and combining the subject and culture. In addition, prospective teachers stated that ethnomathematics-based materials would provide possible contributions such as making students aware of the relationship between mathematics and culture and the importance of culture.