To editor: Wernicke encephalopathy (WE) is an acute neurological disorder caused by a deficiency of vitamin B1 (thiamine), with a prevalence of 1.3% in autopsy studies. 1 Eighty-four percent of patients with WE will develop Korsakoff syndrome, which is characterized by amnesia and confusion. 2 Although WE is more common in alcoholics, it can also be caused by vomiting, malnourishment, and other situations. Hyperemesis gravidarum, a severe form of vomiting in pregnancy affecting 0.3% to 3% of pregnancies, can also cause thiamine deficiency. 3 Although there are no specific diagnostic criteria for hyperemesis gravidarum, it is generally defined as persistent vomiting in pregnancy that has no other identifiable cause. Risk factors of hyperemesis gravidarum include a family history of hyperemesis, multiple gestation, and history of hyperemesis gravidarum. Hyperemesis gravidarum can be associated with other complications such as nutritional deficiencies, esophageal injury, psychosocial effects, and poor fetal outcomes. 3 We report a case of WE associated with hyperemesis gravidarum. This case suggests that providers should have a high degree of suspicion for WE and initiate early treatment in pregnant women with severe vomiting and neurologic symptoms. 4 The patient provided informed consent for publication of this case.