The purpose of this research was to identify nursing interventions performed by MICU and SICU nurses. For data collection this study used the taxonomy of the Nursing Interventions Classification (NIC : 433 nursing interventions) which was modified by McCloskey and Bulecheck(1996). Each of the 433 interventions were identified as used by MICU and SICU nurses. More than 50% of the ICU nurses performed 280 nursing interventions at least monthly. Rarely used interventions included 26 nursing interventions in the childbearing care class. Overall, both MICU and SICU nurses used interventions in the Physiological : Complex domain most often on a daily basis and the interventions in the Family domain least often. The most frequently reported interventions as being used daily in the MICU were chest physiotherapy, airway suctioning and coughing enhancement and, in the SICU, documentation and airway suctioning. There were significant differences between MICU and SICU nurses in 17 nursing interventions childbearing care, cognitive therapy, communication enhancement, coping assistance, elimination management, lifespan care, health system mediation, immobility management, medication management, neurologic management, patient education, psychological comfort promotion, physical comfort promotion, respiratory mangement, risk management and infomation management. The SICU nurses performed there interventions more frequently than the MICU nurses. These findings will help in building of a standardized language for the MICU and SICU and enhance the quality of nursing care.