We report the case of a 30 year-old woman, at 16 weeks of gestational age, with hyperemesis gravidarum. She presented with blurred vision and ophthalmoplagia, VI nerve palsy, distraction and gazing were detected in physical examination. The resonance magnetic imaging was repoeted normal. Her pregnancy was terminated with suspected preeclampsia, but she had gradually decline in GCS and heparin was started with suspected sinus venosus thrombosis. Unfortunately, she died and then in review of brain imaging in the mortality conference, she had typical changes of Wernicke’s encephalopathy. WE is a potentially reversible condition if treated early. We would like to emphasize the importance of prompt thiamine supplementation in pregnant women with prolonged vomiting in pregnancy, especially before starting intravenous or parentral nutrition. Early thiamine replacement will reduce maternal morbidity and fetal loss rate. It was a missed management WE in another center, so we have decided to report it to think of this diagnosis in cases of hyperemesis garavidarum with neurologic symptoms. This report is according to documents.