 Background: Pre-eclampsia affects about 2-8% of all pregnancies. It is one of the leading causes of maternal and perinatal morbidity and mortality hyperhomocysteinemia is considered as a risk factor for endothelial dysfunction and vascular disease. The vascular changes induced by homocysteine are similar to those with pre-eclampsia. The aim of the study is to identify the relationship between maternal serum homocysteine level and the development of pre-eclampsia.  Method and patient:A case control study that was carried out in the Department of Obstetrics and Gynecology at Azadi Teaching Hospital in Kirkuk-Iraq, during the period of eight months from 1st of Feb. till 1st of October 2021. It included 80 pregnant women with singleton viable pregnancy, gestational age of > 20 weeks. They were divided into two groups: Case group included 40 pregnant women who had diagnosed as pre eclampsia (mild and severe) and control group included 40 healthy normotensive pregnant women. Patients with multiple pregnancy, history of medical disease or tacking treatment for hypertension were excluded from the study. Blood sample was taken from each woman for biochemical study, serum homocysteine level was measured using ELISA technique. Result: In this study, pregnant women with pre-eclampsia had significantly higher mean of serum homocysteine compared with controls. Homocysteine level > 8.95 μmol/l is a predictor for pre-eclampsia. Out of 40 women with pre-eclampsia, 42.5% were mild, while the remaining 57.5% were severe. Pregnant women with severe pre eclampsia had significantly higher mean of serum homocysteine compared to those with mild pre-eclampsia. The level of tested biomarkers and homocysteine was tested between the two study groups to assess their rule in pre eclampsia. Conclusions: Maternal serum homocysteine biomarker represents an early non-invasive marker for diagnosis of pre eclampsia and to name the disease according to the severity.