Management of Portuguese Haemovigilance System (PHS) lies within the scope of responsibilities of the steering committee of the Portuguese Blood and Transplantation Institute (PBTI). All the notifications related to haemovigilance and the accountability of the activity of blood establishments and blood services are done through a website. In the process of development of the notification structure and of the web interface, a User Requirements Specification methodology was applied. Requirements and recommendations of Portuguese and European laws, as well as guidelines and definitions of relevant scientific societies and organizations were also taken into consideration. It took two years to complete the process of implementation of the reporting structure. During this time the system was under continuous development following the evolution of the concepts and definitions in haemovigilance as well as of the mainstream tools and tendencies in programming. At this point it can be said that the Portuguese Haemovigilance System is a fully implemented structure that is being constantly elaborated. The online notification process is a fundamental tool for the assessment of transfusion risk.