The aim of this study is to determine the knowledge of secondary school mathematics teachers about their possible misconceptions about ratio-proportion and their solutions to these misconceptions. In the study, a special case study that is one of the qualitative research methods was conducted. Twelve middle school mathematics teachers were included in the study. Besides, data were collected using a semi-structured interview form developed by the researcher. According to the findings obtained through the content analysis, misconceptions were evaluated in 8 categories and the solutions offered for misconceptions were evaluated in 3 categories. The findings indicate that teachers did not mention some of the misconception types mentioned in the literature on ratio and proportion. In addition, it was observed that approximately half of the participant teachers were aware of the misconceptions mentioned, while the other half expressed only a few types of misconceptions. The solution suggestions of the teachers were generally compatible with the methods stressed in the literature. However, it was determined that these solution suggestions were stated by a small number of teachers. From this point of view, it is thought that it is necessary for teachers to obtain information to increase their awareness of misconceptions that they may observe in students.