Purpose:The Objective Structured Clinical Examination (OSCE), an evaluation instrument, requires a validation process to guarantee the measurement of skills related to clinical reasoning. The OSCE is relevant for decision-making during the formation process for professional practice, so the purpose of this study is to determine the content validity and inter-rater reliability of an OSCE, during a physiotherapy undergraduate program for clinical reasoning. Methods: Instrumental design, which identified content validity through internal consistency (Cronbach's alpha), added to recognition of the inter-rater reliability (intraclass correlation coefficient). Results:The instrument demonstrated good internal consistency (0.98) and its concordance is from a substantial to an almost perfect degree of agreement. Conclusion:The OSCE proved to be a suitable instrument to assess the clinical reasoning skill of physiotherapy students; nevertheless, this validation process has limitations in the number of stations and the little application in physiotherapy.