BACKGROUND: Preeclampsia is a rapidly progressing pregnancy-specific multi-systemic syndrome that is the leading cause of maternal and neonatal morbidity and mortality. Lactate dehydrogenase (LDH) is a valuable and potential biomarker for predicting the severity of Preeclampsia. OBJECTIVES: To assess the level of LDH in women with preeclampsia and to correlate its level with the severity of the disease and maternal/perinatal outcomes. PATIENTS AND METHODS: This prospective case-control study was conducted at Sulaimani Maternity Teaching Hospital, Sulaimaniyah, Iraq, from March 1st, 2021, to June 30th, 2022, on 150 pregnant women in 3rd trimester of their pregnancy. Patients (n = 100) were diagnosed with mild and severe Preeclampsia. Serum LDH level was measured and correlated with the severity of the disease and maternal/perinatal outcomes. RESULTS: LDH was significantly (p = 0.001) elevated in preeclampsia groups compared to the control group. The mild preeclampsia group had a mean LDH level of 302.9 ± 138.5 IU/L, while the severe preeclampsia group had a mean level of 488.6 ± 223.4 IU/L. Also, maternal complications, stillbirth rate, and neonatal intensive Care Unit (NICU) admission were higher in women with high LDH levels. CONCLUSIONS: The serum LDH level is high in women with preeclampsia and correlated with the disease severity as well as maternal and perinatal outcomes. So, serum LDH may be a valuable biomarker for predicting the severity of preeclampsia.