This study is a quantitative study that has examined 29 students in grade 8 who have not received a pass grade in mathematics. The focus of this study is in two areas: first, which mathematical abilities do the students have the greatest difficulties in, and second, on the relationship between mathematics difficulties and reading and writing difficulties. Mathematical abilities have been studied using knowledge matrices from the national tests in mathematics. Reading and writing difficulties has been investigated using test results from diagnostic material in the area. The results show that conceptual and problem-solving skills are the most difficult abilities in which previous research also indicates. Procedural ability is the ability where most students show competency, which also is consistent with previous research. The study indicates that there are links between mathematics difficulties and reading and writing difficulties, although it is not possible to show strong correlations in this small study.