OBJECTIVE To improve the patient safety of very-low-birthweight infants in neonatal departments in Germany. DESIGN Multicenter cohort study with a baseline (24 months), an intervention (12 months), and a postinterventional follow-up period (12 months) and time series analysis. STUDY POPULATION Very-low-birthweight patients from 32 neonatal departments in Germany. METHODS Neonatal departments showing a standardized infection ratio of bloodstream infection 10% higher than the expected number (standardized infection ratio ≥1.1) were invited to participate in the study. To reduce the occurrence of primary bloodstream infections, evidence-based bundles to improve catheter maintenance routines, insertion practice, and hand-hygiene compliance were implemented in the participating infirmaries. RESULTS Thirty-four departments participated in the study and 32 reported data. In total, 6,222 very-low-birthweight infants with 231,868 patient-days and 1,405 cases of bloodstream infections were analyzed. In the baseline period the pooled mean bloodstream infection rate was 6.63 (95% CI, 6.17-7.12) per 1,000 patient-days. The bloodstream infection rate decreased in the intervention period to 5.68 (relative risk, 0.86 [95% CI, 0.76-0.97]) and in the 1-year follow-up period to 5.31 per 1,000 patient-days (relative risk, 0.80 [95% CI, 0.70-0.92]). The multivariable time series analysis of monthly aggregated data showed a significant change in the slope for the frequency of bloodstream infections from the start to the end of the intervention (change in slope incidence rate ratio, 0.97; P=.001). CONCLUSION The implementation of an intervention bundle is feasible and can reduce bloodstream infections in neonatal departments. Infect Control Hosp Epidemiol 2016;37:798-804.