Objectives: The aims of this study were to investigate the validity evidence for a novel procedure specific assessment tool of competence in endovascular aortic repair (EVAR) and to establish a pass/fail level for the assessment. Methods: Computed tomography angiography data of a 55 mm in diameter infrarenal aortic aneurysm was implemented into an endovascular simulator. Twenty-three physicians with varying EVAR experiences were video-recorded when performing a standard EVAR procedure on the simulator. Two experienced EVAR operators assessed the participants using the novel rating scale, “EndoVascular Aortic Repair Assessment of Technical Expertise” (EVARATE). Validity was studied according to the framework endorsed by the American Educational Research Association. Results: The EVARATE scale had a high internal consistency (Cronbach's alpha =.90). The inter-rater reliability was acceptable (Intraclass Correlation Coefficient =.68, p =.005). Specific EVAR experience correlated significantly with the EVARATE score (Spearman's rho =.62, p =.002), but general endovascular experience did not. Consequence analysis showed that the EVARATE assessment could distinguish novices from intermediates (p <.01) and from experts (p <.001). A pass/fail score was determined using the contrasting groups' method. Conclusion: This paper presents the initial validity evidence for a novel procedure specific assessment tool, EVARATE, for operator competence in endovascular aortic repair investigated in a simulated setting. The assessment tool can be used to provide structured formative feedback to trainees.