Self-regulated learning takes an important place in social cognitive learning theory. Self-regulated learning includes students' consideration of their knowledge and skills, realization of their competencies by this way and direction their learning process. When individuals assess themselves aspart of this process, it is expected to make an assessment in parallel between their actual achievement level and self efficacy perceptions if they acquired selfregulation skills. Bandura states that this relationship between self-efficacy perception and actual performance is affected by many factors. In general, people who have high self-efficacy beliefs are supposed to have high academic achievement level. Within this framework, the aim of this study is to investigate the relation between 10 th grade students' self-efficacy perceptions and academic achievement levels about natural systems strand in geography course. In this survey study, data were gathered via self-efficacy form and achievement test from 289 10 th high school students. The collected data were analyzed by computer using descriptive statistical techniques and Pearson's correlation coefficienttechnique. The result of the study indicates that thereis a significant but low-level relationshipbetween students' academic achievements and selfefficacy perceptions about natural systems strand.