This study aimed to assess the risks and benefits of the co-administration of lamotrigine and valproate in a pediatric population with refractory epilepsy. Twenty-eight children who received lamotrigine and valproate during co-medication were evaluated. Outcome measurements were established according to efficacy in seizure control, adverse effects, and tolerability. Treatment was considered effective when >50% frequency reduction was obtained. Adverse effects were also analyzed and in patients who presented them the mode of administration was compared with those who did not to verify the importance of this factor. Association of lamotrigine and valproate was considered effective in 64.3% of all patients, regardless of the seizure type. Seizure-free status was obtained in six patients. Drop attacks and secondary generalized tonic-clonic seizures were reduced in five patients, who remained under treatment despite less than the satisfactory (<50%) seizure decrease. Tremor occurred in six patients; urinary incontinence and ataxia in one. Skin rash also occurred, as an early manifestation, in two patients, both with a previous history of hypersensitivity to antiepileptic drugs. Causes for discontinuation were inefficacy of treatment in six patients and presence of adverse effects in two. In our series, seizure control was obtained in most children with refractory epilepsy, some of whom had a previous history of unsatisfactory response to lamotrigine and valproate, either in monotherapy or polytherapy. Adverse effects were uncommon, but skin rash was observed in higher proportions than in other series with lamotrigine or valproate. Nevertheless, these risks may be lessened with slow introduction and by exclusion of patients with a previous history of hypersensitivity.