This paper reflects on how information systems in healthcare contexts can trigger complex processes that produce effects beyond the field of application envisaged by the designers. Drawing on an ethnographic study conducted in an oncology department, this work presents the processes by which a tool designed around (and together with) doctors became the pivotal point of the overall reshaping of medical, nursing and clerical work in the department. Specific focus on the work practices of the nurses shows how this technology has been a key factor in modifying not only their activities but also their professional identity, in which “information management” has become more important than “patient care”.