A summary of the CEN TC 251/4 ''Medical Imaging and Multi-Media'' activities will be given. CEN is the European standardization institute, TC 251 deals with medical informatics. Standardization is a condition for the wide scale use of health care and medical informatics and for the creation of a common market. In the last two years, three important categories-- namely, the Commission of the European Communities with their programs and the mandates, the medical informaticians through their European professional federation, and the national normalization institutes through the European committee--have shown to be aware of this problem and have taken actions. As a result, a number of AIM (Advanced Informatics in Medicine), CEC sponsored projects, the CEC mandates to CEN and EWOS, the EFMI working group on standardization, the technical committee of CEN, and the working groups and project teams of CEN and EWOS are working on the subject. On overview of the CEN TC 251/4 ''Medical Imaging and Multi-Media'' activities will be given, including their relation to other work.