The purpose of this research is to study effects of structured and unstructured study diaries on students' self-requlated learning. Pretest-posttest experimental design with control group was utilized. One of the experimental groups was used structured diaries and other one was used unstructured study diaries. Sixth graders (61 female, 56 male) going to an elementary school in Aegean district participated in this research. Experimental groups wrote their diaries about their studies at home for two months. Data of the research was collected by Self-efficacy For Studying and Scale for Learning Strategies. Also students were interviewed about diaries. Findings have discerned that study diaries have positive effects on students' self-regulated learning and students have positive perceptions about diaries.