We describe the cooperative work of medical secretaries at two hospital departments, during the implementation of an electronic health record system. Medical secretaries' core task is to take care of patient records by ensuring that also do information gatekeeping and articulation work. The EHR implementation stressed their importance to the departments' work arrangements, coupled their work more tightly to that of other staff, and led to task drift among professions. information is complete, up to date, and correctly coded. Medical secretaries While medical secretaries have been relatively invisible to health informatics and CSCW, this case study identifies their importance, and suggests that they and other non-clinical groups should be considered, when developing health care IT. We propose the term 'boundary-object trimming', to conceptualize their contributions to hospitals' cooperative work arrangements.