Wernicke encephalopathy is a potentially life-threatening neurologic syndrome caused by acute thiamine (vitamin B1) deficiency. It is usually associated with excessive alcohol consumption. Less frequently, this syndrome can be caused by persistent vomiting. This is a case report of a 33-year-old woman diagnosed with Wernicke encephalopathy (WE) during the second trimester of pregnancy. The presence of neurological and ophthalmological symptoms in the context of hyperemesis gravidarum led us to evoke the diagnosis of WE, and it was confirmed when specific lesions were found in the brain magnetic resonance imaging (MRI). Luckily for our patient, WE was diagnosed promptly and the signs were reversible after thiamine supplementation. In conclusion, any first line care taker or midwife must know the symptoms of Wernicke encephalopathy because prompt diagnosis and treatment can lead to recovery.