This is a multicenter, non-interventional, prospective study. The observation period comprises at least 6 months, from the initiation of ESL add-on therapy in adult patients with partial-onset epilepsy not sufficiently controlled with one AED, until the first visit that occurs between 6 and 9 months of follow-up. The observation period will end after 9 months of follow-up even if the final assessment is not performed.

To ensure non-interventional status, the neurologist's decision that it is in the patient's best interest to be prescribed with adjunctive ESL has to be made before and independently of his/her decision to include the patient in the study. At all circumstances during the study the patients will be treated and followed according to routine clinical practice. ESL and concomitant medication should be managed by the neurologist according to the respective Summary of Product Characteristics (SPC).In order to reflect real-life practice and to ensure the observational nature of this study, no fixed time-points for study assessment were defined. Intermediate follow-up data will be collected whenever a patient attends to the study's neurologist consultation.

Inclusion Criteria:

• Male or female outpatient, 18 years or older;
• The patient has an established diagnosis of epilepsy and has experienced at least one partial-onset seizure, with or without secondary generalization, within four weeks prior to initiation of adjunctive ESL;
• The patient is not sufficiently controlled on a current antiepileptic monotherapy and, in the neurologist clinical judgment, it is in the patient's best interest to be prescribed with adjunctive ESL;
• The neurologist's decision to prescribe ESL has been made before and independently of his/her decision to include the patient in this study;
• The patient's treatment is in accordance with the SPC of ESL;
• Written informed consent from the patient (or legally acceptable representative, if the subject is unable to provide informed consent).

Exclusion Criteria:

• Known hypersensitivity to the active substance, carboxamide derivatives (e.g. oxcarbazepine or carbamazepine) or to any of its excipients;
• Patient with 2nd or 3rd degree atrioventricular block;
• Patient treated with an experimental drug within four weeks prior to the introduction of ESL;
• Female patient who is pregnant, lactating, or who is planning to become pregnant during the study period;
• Patient starting ESL outside the approved SPC at enrolment.

Adults with Partial-Onset Seizures With or Without Secondary Generalization