INTRODUCTION. Landau-Kleffner syndrome is characterised by acquired aphasia and encephalographic alterations that may or may not be accompanied by epileptic seizures. AIM. To analyse the clinical and encephalographic features and response to treatment of 10 patients with Landau-Kleffner syndrome. PATIENTS AND METHODS. We reviewed the patient records, encephalograms and treatment administered to patients catalogued as having Landau-Kleffner syndrome. RESULTS. The mean age of the patients was 44 months. Of these cases, 60% presented epilepsy when the diagnosis was established and 70% were found to have epileptic status during slow-wave sleep in the encephalographic study. Results showed that 40% corresponded to variants of Landau-Kleffner syndrome. No cause of the disease could be established in any of the patients. In the neuroimaging study, only one patient displayed abnormalities in the magnetic resonance imaging of the brain. All the patients received adrenocorticotropic hormone (ACTH)-based treatment, at a dose of 1 IU/kg/day for one month, administered together with antiepileptic drugs such as valproic acid and clobazam. Convulsive seizures and epileptic status during slow-wave sleep disappeared in all the patients. In the patients without epileptic status, epileptic activity became less frequent, although it did not completely disappear. Aphasia improved considerably, which meant that all the patients were able to enrol in normal schools. CONCLUSIONS. We believe that early diagnosis, together with suitable and timely management of aphasic patients with encephalographic alterations that allow ACTH to be used at low doses, make it possible to offer an early education so as to provide maximum recovery from the disease.