This study aims to explore the effect of conceptual change based instruction accompanied with demonstrations (CCBIAD) on 11(th) grade students' attitudes toward chemistry. The sample consists of sixty-nine 11(th) grade students in two classes in a high school. In the experimental group, CCBIAD was used, whereas in the control group, traditionally designed chemistry instruction was used. The students' attitudes were measured by Attitude Scale toward Chemistry. The results of ANOVA show that there was a significant mean difference between post-test scores of two groups in favor of the experimental group. As a conclusion, CCBIAD has a key role in forcing students' attitudes toward chemistry. (C) 2011 Published by Elsevier Ltd.