The transient loss of consciousness (TLC) is defined as a loss of consciousness abrupt onset, short duration and spontaneous complete recovery. The TLC is a very common cause of medical consultation, especially in the emergency department. Episodes of TLC may be secondary to different entities such as syncope, seizures and functional disorders. In most patients, the TLC is secondary to syncope. However, some studies suggest that up to one in four individuals are wrongly diagnosed as epileptic seizures. This protocol aims to help in the diagnosis of patients with TLC. The various entities that involve TLC will be presented, exploring the elements of the clinical and laboratory tests that may be helpful to reach an accurate diagnosis.