Stevens-Johnson syndrome (SJS) was first described by Stevens and Johnson in 1922. It is an acute mucocutaneous hypersensitivity reaction, involving skin and mucous membranes. This is a rare but life-threatening syndrome. The use of non-steroid anti-inflammatory drugs, penicillin, antimalarials, sulphonamides, and anticonvulsants are common etiologic factors. In this report, we present a case of Stevens-Johnson syndrome related with concomitant use of lamotrigine and valproic acid. A 7 year-old boy referred to emergency clinic suffering from erythematous papules, predominantly on the face and neck, and lesions around the mouth. The patient was under valproic acid therapy for three years with the diagnosis of epilepsy. Because of poor control of the seizures, lamotrigine (25 mg/day) had been added to the treatment one month ago. Dose of the drug had been gradually increased to 50 mg/day in three-weeks period. After one week of this dose, skin eruptions had appeared. In conclusion, the clinicians should be aware of the fact that combined use of lamotrigine and valproic acid increases the risk of SJS especially in children. Patients who undergo anticonvulsant therapy should be informed about possible cutaneous adverse effects and treatment should be discontinued immediately if any rash appears.