A 20-year-old woman developed severe persistent vomiting early in pregnancy. In three months she lost 18 kg of body weight and showed the biochemical features of mild hepatic failure. Four days after starting intravenous dextrose and insulin, she developed short-term memory loss, confusion, ataxia, dysarthria, mild left upper motor neurone facial weakness and upbeat nystagmus. Thiamine was given and no further deterioration occurred. The vomiting persisted until intra-uterine fetal death. Thereafter, her medical, neurological and psychological problems gradually improved. The association of hyperemesis gravidarum, intravenous calorie load and Wernicke's encephalopathy is discussed.