Background: Preeclampsia still becomes a major problem in pregnancies. Various evidences showed that heme oxygenase-1 (HO-1) is very important in pregnancy. This study aims to understand the relationship of heme oxygenase-1 level with onset and severity in normotensive pregnancy and severe preeclampsia. Methods: This is a cross sectional analytic comparative study, the subjects consisted of 26 patients with normotensive pregnancies and 26 patients with severe preeclampsia. Blood samples from women with < 34 / â‰¥ 34 weeksâ€™ normotensive pregnancies and women with severe preeclampsia were taken. HO-1 ELISA kit used to quantitate heme oxygenase-1 level in samples. Results: The level of heme oxygenase-1 in normotensive pregnant women < 34 weeks lower than severe preeclampsia pregnant women < 34 weeks (3.28 Â± 0.46 ng/mL vs 4.20 Â± 0.64 ng/mL, p=0.003, respectively). The median level of heme oxygenase-1 in normotensive pregnant women â‰¥ 34 weeks was 2.96 (2.41â€“4.39) ng/mL, while severe preeclampsia pregnant women â‰¥ 34 weeks was 3.52 (2.88â€“5.43) ng/mL, (p=0.040). The median level of heme oxygenase-1 in normotensive pregnant women was 3.04 (2.41â€“4.39) ng/mL, while severe preeclampsia pregnant women was 3.68 (2.88â€“5.67) ng/mL, (p=0.001). Conclusions: There is correlation between the incidence of severe preeclampsia with heme oxygenase-1 level in < 34 and â‰¥ 34 weeks of pregnancy. There is a significant difference between the level of heme oxygenase-1 in pregnant women with severe preeclampsia and in women with normotensive pregnancy.