PURPOSE The purpose of this study was to identify effective nurse interaction patterns with patients in the emergency department. METHODS For this study, video technology was used to record complete conversations between the nurse and patient. The participants were 28 nurses and 63 patients in the emergency department at one university hospital located in Seoul. The data were collected from November, 2002 to April, 2003. The video recordings were observed for 4 hr for each case and coded using an adapted version of Roter's Interaction Analysis System (RIAS). The data were analyzed using cluster analysis to identify the patterns of nurse-patient interaction. RESULTS Cluster analysis revealed 4 distinct nurse interaction patterns; 1) "closed" characterized by orientation and negative talk, 2) "positive" characterized by positive affective talk, 3) "informative and directing" characterized by task-focused behavior including data gathering, and giving information about medical condition and treatment, 4) "facilitative" characterized by balance of psychosocial and biomedical topics. Patient satisfaction was highest in the facilitative interaction pattern. CONCLUSION The patient centered interaction pattern, balancing information exchange and psychosocial exchange are the most effective interactions in the emergency department, suggesting that effective interaction skill is a core clinical nursing intervention in acute care.