The aim of this study is to reveal the perceptions of fourth-grade primary students about "mathematics lesson" through metaphors and to investigate whether main categories identified regarding the common characteristics of the metaphors differed by gender. A qualitative research design was employed in the study. The study was carried out in the spring term of the 2018-2019 academic year with the participation of 116 fourth-grade students from three public primary schools in a province which is in the western Black Sea Region. The primary data source of the study is "Mathematics Lesson Metaphors Questionnaire ". The data of the study was obtained by completing the blanks in the sentence 'Mathematics lesson is like ………………. Because ………………………….'. The students were asked to write down a metaphor about the mathematics lesson in the first blank and to explain the reasons why they wrote this metaphor in the second blank. The data were analyzed by content analysis method in this study. As a result of the study it is found that the fourth-grade students developed 64 different metaphors about mathematics. These metaphors are gathered in 13 subcategories under the main categories of mathematical knowledge, principles of mathematics teaching, mathematical skills, affective characteristic towards mathematics. At most metaphors are developed in the category of affective characteristic towards mathematics. [This study was presented as an oral presentation at ERPA International Congresses on Education, 10-12 April 2020.]