First seizures are a diagnostic challenge in the emergency room. The differential diagnosis includes epileptic seizures, syncopes and psychogenic non-epileptic seizures. Importantly, amongst first epileptic seizures, acute symptomatic seizures should be distinguished from unprovoked seizures that define epilepsy. The early accurate diagnosis of first seizures is an important issue because of the therapeutic and prognostic implications at stake. In addition to gathering a detailed history, some ancillary tests may be warranted early on in patients' management. In this article, we present some definitions and describe clinical and work up features that might help accurately classify and appropriately manage such cases in the emergency room.