Objective This study aims to describe complications related to ventricular catheter systems with subcutaneous reservoirs (VCSR) (such as Ommaya reservoirs) in pediatric patients with brain tumors. Methods Retrospective analysis of consecutive patients with a total of 31 VCSR treated at the Children's University Hospital of Zurich, Switzerland. Results A total of 20 patients with a median age of 3.3 years at VCSR implantation received 31 VCSR. Overall, 19 complications in 11 patients were recorded: 7 patients had a VCSR-related infection with coagulase-negative staphylococci, 4 of these probably as a surgical complication and 3 probably related to VCSR use. Systemic perioperative prophylaxis was administered in 22 cases, and intraventricular vancomycin and gentamicin were given in 8 cases (none of which subsequently developed an infection). Other complications included wound dehiscence, catheter malplacement, and leakage of cerebrospinal fluid. Overall, 17 VCSR were explanted due to complications. Conclusion Infections were the most frequent VCSR-related complication. In our own institution, the high rate of complications led to the definition of a bundle of measures as a standard operating procedure for VCSR placement and use. Prospective studies in larger patient collectives are warranted to better identify risk factors and evaluate preventive measures such as the administration of perioperative antibiotics and the use of antimicrobial coating of catheters.