Purpose There are limited prospective data on whether the method of flushing affects the complication rate of tunnelled central venous catheters ( CVCs). Patients and Methods During a 25-month period, 203 pediatric patients who had newly placed Broviac-Hickman CVCs were randomly assigned to standard flushing with heparin solution or to experimental flushing with normal saline via a positive-pressure cap. Results Two hundred twenty-one complications were recorded among 75,249 CVC-days ( 2.94 per 1,000 CVC-days). A higher incidence of CVC occlusion ( 83 v 41 episodes; P = .0002) and bacteremia ( 24 v 9; P = .01) were found in the experimental arm. The cumulative probability of developing at least one CVC complication was higher in the experimental arm than in the standard arm ( 65.1% [ 95% CI, 55% to 75%] v 43.8% [ 95% CI, 34% to 54%], respectively; P = .01). No difference was found in either the cause or the frequency of premature removal of CVCs between the two study arms. After a median follow-up of 360 days ( range, 4 to 1,073), CVC survival was similar: 77% ( 95% CI, 66% to 84%) for the experimental arm and 69% ( 95% CI, 53% to 80%) for the standard arm ( P = .7). The factors associated with the occurrence of CVC complication were a diagnosis of leukemia/lymphoma, double-lumen CVC, and experimental flushing. The only factor significantly associated with premature removal of a CVC was a diagnosis of leukemia/lymphoma ( hazard rate, 2.3; 95% CI, 1.1 to 4.7). Conclusion An increased complication rate was found with normal saline flushing, but additional investigation is warranted to clarify whether it is related to saline use or to once-a-week flushing. J Clin Oncol 27: 2059- 2065. (C) 2009 by American Society of Clinical Oncology