OBJECTIVES: To study the impact of a teaching intervention on the rate of central venous catheter-related bloodstream infections (CRBSI) in intensive care patients. DESIGN: Prospective before/after interventional cohort study on medical and surgical intensive care units. SETTING: University hospital with five adult intensive care units. PATIENTS: All patients with a central venous catheter on the five ICUs from September to December 2003 (baseline period) and from March to July 2004 (intervention period). INTERVENTIONS: Educational program with teaching of hand hygiene, standards of catheter care, and preparation of intravenous drugs. MEASUREMENTS AND MAIN RESULTS: The primary outcome variable was the rate of CRBSIs per 1000 catheter days during a baseline period of 4 months and an intervention period of 5 months. The secondary outcome variable was compliance with hand hygiene. Of the patients, 499 patients with 6200 catheter days in the baseline period and 500 patients with 7279 catheter days were monitored in the intervention period. The incidence density of CRBSI decreased from 3.9 per 1000 catheter days in the preintervention phase to 1.0 per 1000 catheter days in the intervention phase (p < 0.001). The risk for CRBSI was significantly higher in the baseline period in both univariate and multivariate analysis. Other independent risk factors were hospitalization in the medical ICU and male gender. Time to CRBSI was significantly longer in the intervention period (median 9 days vs. 6.5 days, respectively; p = 0.02). Compliance with hand hygiene improved slightly from 59% in the baseline period to 65% in the intervention period, but the rate of correct performance of the practice increased from 22.5% to 42.6% (p = 0.003). CONCLUSIONS: Evidence-based catheter-care procedures, guided by healthcare workers' perceptions and including bedside teaching, reduce significantly the CRBSI rate and demonstrate that improving catheter care has a major impact on its prevention.