Background: Nausea and vomiting in early pregnancy is so common that it can be considered a normal part of pregnancy. It is referred to as "morning sickness" although this is a misnomer because symptoms will often persist throught the day. Nausea and vomiting occurs significantly more often in primigravidas and women who were less educated younger-nonsmokers, obese or those with a history of nausea and vomiting in previous pregnancy. Objective: This work aimed at assessing the possible relation between H. Pylori infection and hyperemesis gravidarum (HG). Patient and Methods: Study setting: Al Azhar University Hospitals (Al_ Hussein and Sayed Galal), Duration of study: November 2018 to May 2019. The Study included two groups Group (A): (Thirty) pregnant women with hyperemesis gravidarum in the first trimester attending at antenatal clinics and admitted in the ward in addition to Group (B): (Thirty) normal pregnant women with antenatal care. The pregnant women with hyperemesis gravidarum, aged 18-40 years old and less than 16 weeks gestation. Results: The current study found significant difference between two groups regarding positivity of HPSA. Positive stool antigen were found in 26 out of 30 of hyperemesis gravidarum (86.7%) compared with 11 out of 30 controls (36.7%) and highly statistical significant difference between studied groups as regard H pylori antibodies. Conclusion: There was a significant association between Helicobacter Pylori infection and pathogenesis of hyperemesis gravidarum.