Attempts to modify physician behaviour and reduce practice variation with guidelines have had limited success, largely because of inadequate attention and resources devoted to implementing the guidelines in clinical production environments.While much of what determines the ultimate impact of a guideline has little to do with technology, information technology offers new and powerful methods for guideline implementation. These methods include concurrent and delayed patient-specific decision support. workflow modification. and delayed feedback of aggregate patient data. Ideally, technology should be used to reduce physician cognitive burden and workload while simultaneously achieving guideline objectives.The most effective use of information technology occurs when patient-specific decision support is delivered concurrently with no effort required on the part of the physician. Physician order entry systems provide the most straightforward means of accomplishing this. However, until the clinical information system infrastructure is in place to support patient-specific feedback during an encounter, implementation strategies such as nurse-initiated orders and disease state management remain viable and important alternatives.