Wernicke encephalopathy (WE) is characterized by nystagmus, abducens and conjugate gaze palsies, as well as by unsteadiness of stance and gait, confusion, and apathy. In many cases, however, clinical presentation is incomplete. WE remains somewhat difficult to diagnose because not all cases display the classical triad of symptoms, or because these symptoms can be masked by coma. To diagnose WE, the clinical picture and typical MRI are important, which demonstrate symmetrical damage of the mesencephalic tegmentum, mamillary bodies, medial thalamus, periaqueductal region, floor of the fourth ventricle, and midline cerebellum. WE is a subacute or acute neurological disorder caused by thiamine (vitamin B1) deficiency. This paper presents two cases of WE, one an acute disorder with rapid unconsciousness status and the other with subacute clinical presentation. Both patients were chronic alcoholics.