Peripherally inserted central venous catheters (PICCs) have been increasingly used in pediatric patients. However, little is known about the incidence and risk of complications when using this device in children with cancer. The purposes of this study are to assess the feasibility of PICCs and to determine the risk factors for PICC-related complications in pediatric patients with various types of malignancies. We attempted to place PICCs in 53 patients with a median age of 5 years ranging from 2 months to 20 years. PICCs were used to administer fluid, parenteral nutrition, anticancer agents, antibiotics, and blood products and also for the through-line blood sampling. The duration of catheterization and the incidence of PICC-related complications requiring removal were retrospectively evaluated in association with the diagnosis, sex, age and body weight of the patients, size, insertion site and tip location of the catheters, type of treatment, and duration of leukopenia. PICCs were successfully placed in 109 of 112 attempts (97.3%) in 53 patients, and they were followed for a total of 11,797 catheter days (median placement, 87 days; range, 3 to 512 days). Fifty five PICCs (50.5%) were removed as a result of PICC-related complications with a rate of 4.66 per 1,000 catheter days. The most common reasons for catheter removal were occlusion (n=18), breakage/leakage (15), and infection (10). More than 70% of such complications occurred more than 30 days after placement. The catheter tip location in the superior vena cava or the right atrium might decrease the risk of complications. Other parameters did not influence the incidence of complications. PICCs were found to provide a reliable access for prolonged intravenous administration and blood sampling in children intensively treated for hematologic and solid malignancies, thus leading to a reduction of physical pain and psychological stress in such patients. However, the long-term placement of PICCs may also be related to an increased risk of complications.