Voriconazole trough concentrations more than 1 mg/L are associated with a higher likelihood of success. It is unknown whether these trough concentrations are reached with the current recommended pediatric dosing schedule. We retrospectively analyzed the results of our therapeutic drug monitoring service for voriconazole in 18 children treated at our children's hospital. Thirty-nine voriconazole plasma concentrations were measured. In 44% of patients, the first voriconazole concentration was below the target. Dose adjustment eventually resulted in plasma concentrations within the predefined target range in all patients. Given the high proportion of patients with subtherapeutic concentrations, monitoring plasma concentrations should be performed routinely in pediatric patients receiving voriconazole.