Due to the advances in high-tech technology in the operating theatre, the increased number of persons involved, and the increased complexity of surgical procedures, medical errors are inflicted. To answer the main question: How to improve patient safety in the operating theatre during surgery? this thesis is split into three parts. Part A focuses on the processes concerning ‘planning, acting/ performing and recording’ surgical procedures. Currently, no surgical protocol uniformity exists and most operative notes are still dictated postoperatively. Operative notes are sometimes not written according to the guidelines for operative note writing, are subjective, and do not fully correspond to the actual events observed in the video recordings of that particular procedure. Part B focuses on the implementation of a Time Out Procedure plus Debriefing (TOPplus). Results show that operating team members hold different perceptions of communication, teamwork and situation awareness. Designing TOPplus by means of the user-centred participatory design approach, in combination with the context-specific design principles, proves advantageous for implementing the procedures and acts as a catalyst for related patient safety initiatives. Part C focuses on improving the working conditions of the operating team. During surgery problems are encountered within the sensorial, cognitive, physical, and environmental domain. Surgeons performing minimally invasive surgery experience physical discomfort in mainly neck, shoulder, and back. Although the importance of ergonomics is recognised, only few surgeons are aware of general ergonomic guidelines to improve their working conditions. Finally, product evaluation of two types of surgical lights shows that specific disciplines require different lights.