Intraosseous (IO) access offers a fast and reliable route for administration of fluids and drugs when intravenous (IV) accesses like umbilical, peripheral, or peripherally inserted central lines fail in critically ill neonates. Several medications can be successfully administered via the IO route, however only limited information is available regarding IO administration of antiviral agents.We present the case of a 2-week-old neonate, admitted to the Neonatal Intensive Care Unit (NICU) due to suspected meningitis, who received acyclovir through IO infusion after the venous access was lost and a new one could not be established. No complications were reported within 12 months of follow up.This report highlights the feasibility of IO acyclovir infusion when IV accesses fail in a critically ill neonate.