This study investigated the effectiveness of 5E learning cycle on 6th-grade students' achievement of cell concepts, and their scientific epistemological beliefs. Epistemological Belief Questionnaire and the Cell Concept Test were administered as pre-test and post-test to a total of 153 sixth grade students in four intact classes of an elementary school. Two classes were randomly assigned as control and experimental groups. Experimental groups received 5E learning cycle instruction and control groups received traditional instruction. The data were analyzed using multivariate analysis of covariance. Results showed that treatment had a significant effect on the collective dependent variables. Univariate ANOVAs indicated a statistically significant mean difference between experimental and control groups regarding cell concepts achievement and epistemological beliefs in the favor of experimental groups. (Contains 2 tables.)