Health care information technology (IT) systems manage administrative and clinical processes more accurately and efficiently. However, their effects on clinical work flow are still not fully understood. In this article, we investigate the bar‐coded medication administration (BCMA) system for its effect on nurses working in inpatient departments. Evaluation is applied by examining work deficiencies before and after the IT system implementation based on a proposed nursing work model. A list of nurse‐perceived risks of work deficiencies related to the current BCMA system has been identified. Results show five main deficiencies that are mainly related to aspects of the IT environment and work schedule/process, including increased workload, IT systems downtime, unclear orders/task schedules, reduced time for patient‐care tasks, and redundant documentation. This study emphasizes the importance of understanding the reciprocal relationship between IT implementation and health care work system. © 2012 Wiley Periodicals, Inc.