BACKGROUND: To investigate the usage patterns of sedatives, analgesics and neuromuscular blocking agents (NMBAs) in patients requiring mechanical ventilation more than 72 hours in intensive care units (ICUs) of Korea. METHODS: A total of 536 patients continuing mechanical ventilation more than 72 hours had been enrolled among the twenty-one ICUs of Korea from May 2003 to July 2003. Data about mechanical ventilation, the use of sedatives, analgesics, and NMBAs were prospectively collected for four weeks. We analyzed the patterns of using these drugs and effects on outcomes. RESULTS: More than half of the patients (50.4%) received sedative drug alone. Most commonly used sedatives and analgesics were midazolam and morphine. NMBAs were administered in 41% of the patients. Volume controlled ventilation mode was associated with more frequent use of NMBAs. There were no significant differences in outcome variables among the usage patterns of sedatives, analgesics and NMBAs. CONCLUSIONS: Our investigation shows that analgesics were much less frequently used in the intensive care units of Korea compared with the use of sedatives. And the use of NMBAs were quite a common.