In the last decades, major complications in surgery have emerged as a significant public health issue, so the practical implementation of safety measures to prevent injuries and deaths in different phases of surgery is required. The introduction of novel technologies in the operating theater, such as surgical robotic systems, opens new questions on how much and in which way the safety can be further improved. Computer Assisted Surgery (CAS), in combination with robotic systems, can greatly help in enhancing the surgeons' capabilities providing direct patient and process-specific support to surgeons with different degrees of experience. In particular, the application of Augmented Reality (AR) tools could represent a relevant step towards safer clinical procedures, improving the quality of healthcare. This chapter describes the main areas involved in an AR system, such as computer vision methods for identification of areas of interest, surgical scene description and safety warning methods. Recent advances in the field are also presented, providing as an example the Enhanced Vision System for Robotic Surgery (EnViSoRS): an AR system to provide assistance towards the protection of vessels from injury during the execution of surgical procedures with a commercial robotic surgical system.