Physician-centered design for computerized physician order entry (CPOE) systems overlooks the collaborative, multi-professional nature of medical work. We analyzed the compatibility of the conceptual model of inter-professional workflow underlying a CPOE system with real-life workflow in the medication ordering and administration process. We conducted twenty-three semi-structured interviews with key informant users and analyzed the handwritten documents and computerized printouts used in daily work in a Dutch academic medical center. The interview transcripts were analyzed on the basis of three conceptual themes in the inter-professional workflow: division of tasks, flow of information, and task coordination. The CPOE system fundamentally reorganized the existing work procedures of the three professional groups involved, mainly by reassigning tasks and by reallocating areas of expertise. Although the system improved the flow of medication-related information from physicians to nurses or pharmacists, this flow was only in one direction; the system did not allow information transactions in the reverse direction. It also failed to coordinate the medication-related tasks of professionals from different disciplines. To maintain the necessary level of coordination, the professionals had been obliged to consider additional methods of communication, such as phone calls or face-to-face discussion. We identified several workflow integration issues after the implementation of a CPOE system. Our insights into these issues can help ensure that system design or redesign properly integrates all professional groups' tasks, information, and areas of expertise into those of the physicians. Only then can these systems support the actual inter-professional workflow in the medication process.