Lack of clinical competence can endanger the patient's safety and reduce the quality of providing health care services. The aim of this study was to examine the impact of formative Objective Structured Clinical Examinations (OSCEs) with immediate verbal and visual feedback on the clinical competence of fourth-year nurse anesthesia students. This was a single blind quasi-experimental study with a pre-test/post-test design in compliance with the CONSORT (Consolidated Standards of Reporting Trials) statement. Forty-eight students were allocated to intervention (n=24) and control (n=24) groups. During the academic semester, the students of the intervention group attended 3 sessions of formative OSCE (5 stations) with immediate verbal and visual feedback. In the control group, however, the students received in-person feedback according to curricular routine. The data collection tool included two sections. The first section included a questionnaire to collect demographic information such as age, sex, grade point average and marital status. In the second section, clinical competence of students was measured by Common Clinical Assessment Tool (CCAT). The collected data were analyzed by Analysis of Covariance, paired T-test, Chi-square, and Fischer's exact test in SPSS, version 16. Comparing post-test scores by ANCOVA showed a significant difference between groups (p=0.001) because there was a significant positive change in the overall clinical competence score in the intervention group after receiving formative OSCE. This study showed that regular implementation of formative OSCEs in nurse anesthesia education fosters learning and has a positive effect on improving students' educational behaviors and helps them learn more efficiently. However, it is recommended to conduct more studies with a larger number of participants to confirm this conclusion.