An electronic medical recording (EMR) system is enlightened as a solution for deciding which nursing diagnosis was selected on the basis of a computerized system; it can help collect and analyze lots of diverse data in an objective way. But there are few reports of successful electronic nursing diagnosis on EMR systems. This study was to develop the objective decision system prior to nursing diagnosis and to adopt it in the Severance EMR system. We adopt a new concept, situational variables, as the key elements of the nursing process, based on the items of nursing intervention. It enables appropriate nursing diagnosis through complex clinical objective data (laboratory results, vital signs, etc.). Through these elements between nursing intervention and nursing diagnosis, we can create reliable evidence-based nursing diagnoses successfully, and make possible fast settlement of nursing intervention in the various clinical fields.