The focus of this study lies within gender coded musical instruments. This concept concerns the unconscious thought of musical instruments as either feminine or masculine. The aim of this study is to acknowledge the existence of this concept amongst pupils in Swedish upper secondary schools, and to demonstrate how it can affect pupils’ choice of main instrument. The study presents earlier studies that show signs of the existence of gender coded instruments. It also explores the concept of sex and gender in different situations. These include the use of gender in the Swedish language, in music, and in an ensemble situation. Fifteen pupils from two different schools were interviewed, and the conclusion is that the gender coding exists. When the pupils were asked to categorise different instruments as feminine or masculine, the results revealed that singing and piano were considered feminine. Some of the masculine instruments were electric guitar, electric bass, and drums. According to the pupils, the reasons behind their main choice of musical instrument can be put into five different categories. These are; Role models, Parents’ influense, the accessibility of musical instruments, Norms and Biological stereotypes. Three of these categories; Role models, Norms and Biological stereotypes are also what they believe are reasons behind gender coded musical instruments. The aim of this study is to raise awareness of this situation as the Swedish school values show that schools and their teachers are supposed to work towards equality between the genders, a task which cannot be done if this continues.