Valproic acid (VPA) has found clinical use as an anticonvulsant and mood-stabilizing drug, primarily in the treatment of epilepsy. VPA mechanism of action is believed to be the inhibition of the transamination of GABA and also blocks the voltage-gated sodium channels and T-type calcium channels, which makes VPA a broad spectrum anticonvulsant drug.Seizures can present at any time before or after diagnosis of a brain tumor. The risk of seizures varies by tumor type and its location in the brain. It was believed that preventing seizures with antiepileptic drugs was effective and necessary, but it was later concluded that seizure prophylaxis was ineffective in people with brain tumors. However, postoperative seizure prophylaxis after brain tumor resection is still controversial.The aims of the study were to assess valproic acid effectiveness in postoperative seizure prophylaxis in pediatric brain tumor patients, to evaluate the safety and toxicity profile of VPA (valproic acid) administration in brain tumors patients at CCHE, to determine any correlation between the toxicity and the level of VPA in brain tumors patients at CCHE, and to evaluate the impact of the implementation of clinical pharmacy service at the neuro-oncology department CCHE.