Many students majoring in biology education at university find genetics as a quite complicated and difficult subject. A reflective journal has been used widely in teacher education to improve students' performance. This study aims to describe the role of the reflective journals for biology education students ina genetics course. The subjects in this research were 53 students of biology education at a private university in Indonesia who were pursuing their third year of education. The data were collected from the Likert scale questionnaire, students' reflective journals, and online feedback sheet. The result showed that the reflective journals had roles for biology education students when learning genetics, namely concept understanding, attitudes and values, and learning experiences. The benefit of reflective journals in students' attitudes and values achieved the highest average value based on the Likert scale questionnaire with very high interpretation criteria in all item statements. Most students gave positive comments about the reflective journal activity and proposed to apply it in another course. Some students also provided suggestions about the technical implementation and time duration. The reflective journals activity benefits the students, as well as helping the lecturer to evaluate the learning process in the genetics course.