This article reports three patients with epilepsy who had the main manifestation of acute cognitive impairment. All three patients had the initial symptom of acute cognitive impairment， among whom two patients also had other types of seizures， such as cognitive seizures with focal perceptual impairment， automatic seizures with focal perceptual impairment， and generalized tonic-clonic seizures， and one patient only presented with cognitive seizures. Although all three patients had a significant improvement in cognitive impairment during the interictal period， neurological scale assessment still showed the presence of cognitive impairment. Magnetic resonance imaging for the three patients showed multiple old infarcts in the cerebral cortex and the subcortical region， with abnormalities in the hippocampus in two patients. Electroencephalography recorded epileptiform discharge in all patients. All three patients showed a reduction in seizures after the application of antiepileptic drugs， among whom one patient showed no recurrence of seizures. Follow-up showed that two patients did not have aggravation of cognitive impairment， and one patient progressed to dementia. Epileptic patients with the main manifestation of acute cognitive impairment may experience misdiagnosis or missed diagnosis， and such patients should be taken seriously in clinical practice. ［Journal of International Neurology and Neurosurgery, 2024, 51(4): 52-59］