Background.Blood stream infections are a common and serious complication of central venous catheters (CVCs). To decrease catheter colonization, some authors advocate tunneling the catheter in the subcutaneous tissue during insertion. This technique has proved effective in adults, but there are no data on its safety and efficacy in critically ill children. Our objective was to evaluate the efficacy and safety of subcutaneous tunneling of short term, noncuffed CVCs for the prevention of CVC-related infections in critically ill children.Methods.A prospective randomized controlled trial was performed at a tertiary children’s medical center in Israel and included children ages 0 to 18 years admitted to the pediatric intensive care unit or the pediatric cardiac intensive care unit from September 2000 to April 2001 who required placement of a femoral central venous catheter for >48 h. The children were randomized for tunneled or nontunneled insertion. The main outcome measures were bacterial colonization of proximal and distal catheter segments tested by semiquantitative technique and infectious or noninfectious complications of the CVC.Results.Of 98 eligible children, 49 received tunneled catheters and 49 received nontunneled catheters. Patients’ age ranged from 1 month to 16.5 years (mean, 3.07 ± 2.48 years). There were no significant differences between the groups in age, sex, disease severity [Pediatric Risk of Mortality III (PRISM) score], duration of catheterization and underlying diseases. Bacterial colonization was found in 11 (22.4%) catheters in the nontunneled group compared with 3 (6.1%) in the tunneled group (P= 0.004). Proximal segment colonization occurred in 7 (14.2%) nontunneled catheters and 2 (4.8%) tunneled catheters (P= 0.07), and distal segment colonization occurred in 3 (6.1%) and 9(18.3%) tunneled and nontunneled catheters, respectively (P= 0.053). The main pathogens were coagulase-negative staphylococci,Pseudomonasspp. andKlebsiellaspp. There was no statistically significant difference between the groups in the rate of bloodstream infection (2 in the tunneled group, 3 in the nontunneled). Except for 1 case of subcutaneous hematoma, which resolved, there were no immediate or late complications of the tunneling procedure.Conclusion.Subcutaneous tunneling of CVCs in the femoral site is a safe procedure and decreases significantly the rate of CVC colonization in critically ill children.