Background: Prevalence of hyperemesis gravidarum varies from 0.3 to 1.5% of all live births. The exact cause is not well known and is probably multifactorial. It is the most common cause of hospitalization in the first half of pregnancy and second only to preterm labor for pregnancy overall. The etiology of emesis gravidarum remains unknown. But a number of possible causes have been studied as endocrinal, immunological, psychological, metabolic, genetic and even infectious such as helicobacter pylori infection. Aim of the Work: To assess the value of screening for helicobacter pylori seropositivity in hyperemesis gravidarum for better evaluating and improving the cure rate especially in resistant cases. Patients and methods: A prospective controlled comparative study was conducted on 100 pregnant women in the first trimester, where 50 of them were suffering from hyperemesis gravidarum (group A) and another 50 healthy women were chosen as a control group (group B). They were recruited from the outpatient clinic of Al-Galaa Maternity Teaching Hospital, Cairo, Egypt from January 2019 till June 2019. After approval of the local ethics committee, a written consent was obtained from each woman before inclusion in the study. Fasting and post prandial sugar, Liver and kidney function tests, thyroid function tests, CBC, urine and electrolyte examination as well as serum examination for IgG of helicobacter pylori were done for each one. Results: Serum helicobacter pylori IgG antibodies seropositivity and acetonuria was significantly higher in group A than in group B while serum sodium and potassium levels were significantly lower in patients with hyperemesis gravidarum than control group. Conclusion: The treatment of H. Pylori infection may reduce the risk of hyperemesis gravidarum and its complications.