Busulfan is commonly used in the conditioning regimen for hematopoietic stem cell transplantation. Due to the risk of seizures associated with its use, prophylaxis with an anti-seizure drug is required. We prospectively evaluated the effectiveness of oral levetiracetam in children and adolescents for the prevention of busulfan-induced seizures. None of the 64 patients included in the study experienced seizures during the conditioning therapy or side effects that required discontinuation of the drug. Our results suggest that oral levetiracetam is effective in this setting.