The aim of this study was to investigate the effect of students' learning styles on their chemistry achievement and attitudes toward chemistry as a school subject. One hundred seventy nine 9th grade and 151 10th grade students taking chemistry courses from different high schools were enrolled in the study. The Learning Style Inventory was used to determine students' learning styles. This scale was based on Grasha's criteria and consisted of four clusters obtained from six learning styles. The first cluster consisted of dependent/avoidant/participant/competitive; the second cluster included participant/dependent/collaborative; the third cluster contained collaborative/participant/independent; and the fourth cluster consisted of independent/collaborative/participant learning styles. Also, Attitude Scale Toward Chemistry was administrated to the students to measure their attitudes toward chemistry as a school subject. MANOVA was used for statistical analysis. Results showed that there was a significant effect of learning styles on students' attitudes toward chemistry and their chemistry achievement. Students in learning style clusters 3 and 4 had better understanding of chemistry concepts and more positive attitudes toward chemistry as a school subject. (Author)