Background: The purpose of this study was to evaluate the effectiveness of a simulation-based workshop with ultrasonography instruction in reducing mechanical complications associated with central venous catheter (CVC) insertion. Methods: A single-center prospective cohort study was conducted in the medical ICU and respiratory step-down unit of an urban teaching hospital. Fifty-six medical house staff members were trained prior to their rotations over a 6-month period. The data on mechanical complication rates after the implementation of the workshop were compared with previous experience when no structured educational program existed. Results: There were 334 procedures in the preeducation period compared to 402 procedures in the posteducation period. The overall complication rate, including placement failure, in the preeducation and posteducation period was 32.9% and 22.9%, respectively (P<.01). Placement failure rate decreased from 22.8% to 16.2% (P =.02), and arterial punctures decreased from 4.2% to 1.5% (P =.03). Ultrasonography usage increased from 3.0% to 61.4% (P<.01). Multivariate analysis demonstrated that interns were more likely to cause overall mechanical complications compared with fellows and attending physicians in the preeducation period (P =.02); however, this trend was not observed in the posteducation period. Catheter site and ultrasonography usage significantly affected the overall complication rate in both periods, and ultrasound-guided femoral CVC was the safest procedure in the posteducation period. Conclusions: Implementation of a prerotational workshop significantly improved the safety of CVC insertion, especially for CVCs placed by inexperienced operators. We suggest that simulation-based training with ultrasonography instruction should be conducted if house staff members are responsible for CVC placement.