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Transient global amnesia (TGA) is a sudden and reversible amnesic syndrome, impairing totally the anterograde, and to a lesser extent retrograde, episodic memory. It occurs mostly at around 60 years of age, lasts less than 24 hours and has the distinctive characteristic to be triggered in most cases by a stressful physical or psychological event. Diagnosis is based on clinical grounds, but an additional work-up is often necessary to rule out other causes of acute amnesia, such as stroke or epilepsy. Diffusion-weighted magnetic resonance imaging shows in most cases the delayed appearance of punctate hippocampal hyperintensities that are also reversible. The cause of TGA is unknown but it is thought that neurons within the CA1 field of the hippocampus are especially vulnerable to the consequences of stress. TGA is a unique clinical model for the study of the neuropsychology of memory.