Today, surgeons accept computer assisted technologies as important tools to enhance the treatment of a patient. The positive impact and acceptance of computer assisted technologies could be increased to a great extent, if all methods and devices used for diagnosis and treatment of a patient are better co-ordinated and more finely tuned. Often computer assisted treatments cannot be performed due to a lack of communication between hospital departments, useless patient data, deficient interfaces, etc. Risks for the patient and potential errors within the treatment are often unrecognised, as up to now the safety of computer integrated surgery is only product-, device and security oriented. We have developed a new approach for a safety architecture, which includes safety aspects considering patients, users, interdependencies and interactions of computer assisted methods and apparatuses.