Abstarct: Safety problem in human robot interaction (HRI) is very important and has always been considered. Definition of a safe interaction is different in each practical field; and regarding to its special characteristics, safety preparation and evaluation strategies are different. A lot of professional works have been done in each field; and lead to publish an international safety standard in that field. Although, many researches have been established in the rehabilitation field; but, a special safety criterion have not been introduced for quantitative safety evaluation until now. In this thesis, safety evaluation in design and control of rehabilitation robots is studied. History of robots safety is studied and applicable safety standards for rehabilitation robots are identified and introduced. Safety evaluation criteria and its providing strategies are obtained by studying this classified researches and standards. After that, realization of identified strategies is expected for an elbow rehabilitation robot with cable actuator. Performance of the elbow rehabilitation robot with different control strategies which is designed for safe human-robot interaction is assessed by proposed safety criterion.