Intensive monitoring may be required in the diagnostic evaluation and therapeutic management of patients with intractable epilepsy. This article discusses the indications for intensive monitoring, including the differential diagnosis of seizures, their characterization and classification, the quantitative evaluation of therapy, critical appraisal of medical therapy, and evaluation for surgical therapy. The advantages and disadvantages of the available monitoring modalities are reviewed for each indication. By recognizing which patients could benefit from intensive monitoring and by selecting the appropriate monitoring modality, the physician helps to assure the correct diagnosis and optimal therapy of epilepsy.