Background: Hyperemesis gravidarum (HG) is a severe form of nausea and vomiting in the first trimester of pregnancy. It is considered a benign condition, but severe complications, fortunately rare, have been reported. Frequently, this condition is associated with a perturbed liver function tests, which remains without severe consequences. The clinical presentation may be suggestive of an acute liver injury (ALI), especially as the end of the first trimester approaches, pregnancy specific and non-specific liver diseases should be considered. Case: A 28-year-old primigravida, 14-week pregnant woman affected by hyperemesis gravidarum, developed high transaminases level and spontaneously low prothrombin time (PT) ratio. An ALI was suspected as transaminases were very high and our patient was at the end of the first trimester. An exhaustive etiological work-up was negative. In the second line, the factor V assay was conducted, which showed a normal activity, and the vitamin K level was low. We therefore concluded that it was hyperhemesis gravidarum complicated by fluid and electrolyte disorders and vitamin K deficiency. She had parenteral rehydration and a proton pump inhibitor. She received intravenous vitamin K 10 mg daily for three days. The outcome was excellent without any maternal or fetal impact. Conclusion: Hyperhemesis gravidarum is a common condition in the first trimester of pregnancy that usually has a favourable outcome. However, it is important to be attentive to possible complications, including vitamin K deficiency with its maternal and fetal consequences.  On the other hand, in case of major disturbance of the liver function tests, we should not overlook acute liver injury and should not hesitate to initiate an adequate etilogical investigation.