This study aims to investigate the effects of concept maps, together with conceptual change texts, given to 11th grade students' on the subject of molecules carrying genetical information. The semistructured individual interviews were conducted with 5 upper class students to find misconceptions related to the subject. A success test was developed in the light of information taken from both literature and also interviews. This test was applied to the control group, who was taking traditional educational courses, and to the sample group students who were taking classes using concept maps and conceptual change texts together. The data was collected from 50 students; the groups consisted of 25 in the sample group and 25 in the control group. It was found that the conceptual change texts accompanied by concept mapping instruction produced a positive effect on students' understanding of the concept. The average percent of correct responses of the experimental group was 61.6% and that of the control group was 53.6% after treatment. (Contains 6 tables.)