The aim of this study is to investigate high school students' geometry course achievement according to their learning styles. 11th grade students in Izmir constitute the general universe of the research and the sampling of the research comprises of 11th grade students in Karabaglar district. Sampling of the research consists of total 50 high school students, determined by using appropriate sampling method. 60% (n=30) of these students are female and 40% (n=20) of them are males. Both quantitative and qualitative research methods were used depending on the main and sub-questions of the research. Kolb's Learning Style Inventory was used in order to determine the learning styles of the students. As a result of the research, it was found out that most of the students who have diverging learning style were female students (77.8%), most of the students who have accommodating learning style were female students (75%), the number of male students (47.4%) and the number of female students (52.6%) who have assimilating learning styles are close and it was found out that, among the students who have converging learning style, female students (55.6%) were more than males. It was determined that there was no statistically significant difference between the geometry achievement scores according to learning styles and that the students' geometric achievement means were statistically significant according to gender. It was proposed that taking learning styles into account in the regulation of education environments can help to increase achievement.