The etiology and pathogenesis of preeclampsia remain unknown but it has been proposed that genetic predisposition to coagulation abnormalities contributes to the development of preeclampsia by increasing the thrombotic tendency. This study was conducted to estimate one of the thrombosis variant, prothrombin G20210A Mutation, as a risk factor for preeclampsia. One hundred and seventeen preeclamptic women and 102 normal control group were included in this study, both groups were in the 3^rd trimester of pregnancy. A positive association was fond between maternal age over 35 years [OR = 8; CI: 1.54-44.23], previous preeclampsia [OR = 6.34; CI: 2.16-19.96], positive family history of hypertension [OR = 3.44; CI: 1.28-9.60], diabetes mellitus [OR = 10.14; CI: 1.24-221.18], history of recurrent abortion [OR = 24.05; CI: 1.39-416.94], intrauterine fetal death [OR = 19.5; CI: 1.11-342.65], and fetal anomalies [OR = 8.42; CI: 1.06-180.0] and preeclampsia. The frequency of heterozygous carriers of the prothrombin G20210A mutation in preeclamptic women [6.8%] was higher than that in controls [2.9%], but the difference was statistically non-significant. However, the frequency of prothrombin mutation was statistically higher in severe preeclamptic women [14.7%] compared to women with mild preeclampsia [3.6%] [P<0.05]. This indicated that prothrombin mutation is associated with severe preeclampsia and worsens the prognosis of the disease.