The aim of this study is to determine the effect of concept cartoons on 7th grade students' acquiring the concepts in "The Structure and Properties of Matter" chapter. To reach this aim concept cartoons involving students' preconceptions and alternative conceptions about the concepts in the unit were developed. The data of the research was collected via the Structure and Properties of Matter's Concept Test (SPMCT) and semi-structured interviews. The sample of the research consisted of 49 grade 7 students in total, 24 students in experimental group and 25 students in control group. SPMCT prepared by considering the alternative conceptions obtained via the outcome of literature analysis was applied as a pre-test. And then, the unit of "the structure and properties of matter" with prepared concept cartoons was studied. At the end of the study, SPMCT was applied to the students as a post-test. At the end of the research, it was ascertained that students had varied alternative conceptions about studied concept, some of them learned the concepts of the structure and properties of matter at a level of knowledge, but were inadequate in applying them. In addition, the students chosen from the experimental group were interviewed with the intent of promoting the test results. As a result of analyzing the test and interview, it was ascertained that the application decreased the alternative conceptions on the structure and properties of the matter existing in students, did not reveal new alternative conceptions and got the students comprehend the subjects better.