Background: Learning environment has a direct effect on students' self-efficacy. In clinical training, instructors should provide the support for their students to cope with this stressful environment and to enhance students' achievement. We examined the role of the clinical instructor and students' self-efficacy by two validated questionnaires to find the relationship between these two factors. Objectives: This study aims to investigate the relationship between the role of the clinical instructor, students' self-efficacy, and academic achievement. Subjects and Methods: This is a correlational and predictive study; the study population included all fifth-year undergraduate (number=154) medical students at the Faculty of Medicine, Suez Canal University (FOM-SCU). The instruments were Medical Achievement Self-Efficacy Scale (MASS) to measure students' self-efficacy and Nursing Clinical Teacher Effectiveness Inventory (NCTEI) to find out the characteristics of the effective teacher from the students' point of view. The academic achievement of the students was measured through their scores in the OSCE exams in six clinical rounds. Results: The descriptive statistics of the two factors of the MASS questionnaire reveals that the students were highly satisfied with factor regarding outcome expectancy with mean= 3.59. The descriptive statistics of the six factors of the NCTEI questionnaire reveals that the students were highly satisfied with factor 5 (mentoring) with mean= 4.96. The Pearson's correlations revealed positive correlation between the construct of self-efficacy and all factors of NCTEI and academic achievement. Multiple linear regression analysis of the mean scores of student's responses to MASS revealed significant predictions. Conclusion: The study concludes that medical students positively perceive their self-efficacy, which influences the development of their interests and goals. So, this study highlights the importance of the role of the clinical educator, especially as a mentor, for enhancing the perceived self-efficacy of the students.