A seizure is defined as the clinical manifestation resulting from an excessive and abnormal discharge of a population of neurones. The individual lifetime risk of developing a non-febrile seizure is about 5% and around a third of patients will experience further seizures and be diagnosed as having epilepsy. When assessing a possible first seizure, assuming that the patient has recovered and is not in an emergency situation, the first question is whether the paroxysmal event was a seizure. There are many seizure imitators, some of which can be fatal if missed. These include cardiac syncope due to arrhythmias, valvular abnormalities or ischaemia, hypotension, hypoglycaemia and TIAs. Ultimately, the diagnosis of a seizure is clinical and is best established by taking an accurate history. An accurate description of the paroxysmal event is paramount. So the patient should ideally bring a witness to the consultation, allow the clinician to contact a witness by phone, or provide a written description of the paroxysm. Further features to be established include type of seizure (generalised or partial) and timing (early morning or nocturnal). The past medical history should be probed for previous syncopal events or possible seizures. Once a putative diagnosis of a seizure has been made, the second question is whether the seizure was provoked or not. Examination should include assessment of the level of consciousness and orientation, and the cardiovascular and nervous systems. In the patient who has fully recovered from a first seizure NICE recommends measuring plasma glucose, and electrolytes including calcium, and a 12-lead ECG. Referral to an emergency department for urgent neuroimaging and lumbar puncture should be considered if the patient has not fully recovered, and/or if risk factors are present. If the patient has fully recovered, guidelines recommend referral to a first seizure clinic for review by an epilepsy specialist.