ATHENA DSS combines patient information from VistA with an automated knowledge base of hypertension to generate patient-specific recommendations for management of hypertension that are displayed to primary care clinicians in pop-up windows in the VA�s Computerized Patient Record System (CPRS) when the record for appropriate patients is opened on the day of scheduled primary care clinic visits. The ATHENA DSS pop-up provides advice on adequacy of control of blood pressure and specific recommendations for drug therapy of hypertension, a visual display of the patient�s medication history and concurrent blood pressures, evidence supporting the main recommendations, and other information. We deployed the system at three VA medical centers--Durham, San Francisco, and Palo Alto�and conducted a clinician-randomized trial. We logged data on use of the system, monitored comments entered by clinicians, and conducted a questionnaire survey of clinicians. We planned analyses of impact on clinician prescribing and patient blood pressures. We planned preparation for dissemination of the system to additional VA medical centers.