The study reported in this article examines the implementation of the same software in 3 emergency departments from different Belgian hospitals. It was experienced and perceived very differently as a failure or a success by the units' staff. The software integrates different functionalities, which can be chosen and customized by some members of the units themselves. We will look at the three processes of implementation to find out different plausible explanation for their 'failure or success'. Our approach is developed through the qualitative methodology of case studies. The translation theory is presented as a renewal way of thinking the perceived 'successful or failed' implementation of a new information system and a guide for new project in emergency department.