Technical skills have traditionally been taught by "learning by doing". This teaching method is mainly associated with potential risks for patients. Teaching technical skills using simulators has emerged in recent years but their effectiveness has not been adequately tested. The objective of this study was to examine the effectiveness of a central venous catheterization (CVC) training program using a simulator.1) Twenty residents were randomized to either receive a training program using a simulator on CVC (simulator group, n=10) or not (non-simulator group, n=10). They were evaluated for their technical competence in performing CVC on patients and their personal concerns about their first experience of CVC.2) There was no difference between the two groups in resident and patient characteristics; however, the simulator group scored significantly higher in the 4-point performance score than the non-simulator group (2.80±0.33 versus 2.30±0.48, P=0.035).3) The completion rate of CVC was higher in the simulator group (90% versus 60%, P=0.12), and they required fewer attempts at needle insertions (1.67±0.71 versus 3.00±1.26, P=0.022).4) Residents in the simulator group noted the effectiveness of this program more frequently than those in the non-simulator group (86% versus 36%, P=0.057) and showed fewer concerns about their first experience of CVC on patients.5) The CVC training program using a simulator improved residents' skills and is likely to be effective to diminish the fears of residents about performing CVC on patients.