Background: Preeclampsia is a critically important disease of pregnancy, one of the major causes of fetal and maternal morbidity and mortality. Cytokines are implicated in the pathogenesis of preeclampsia in studies done in developed countries. However, few, if any studies have been done in our population. It is also important to know the relationship between serum levels of cytokines and the severity of preeclampsia as this may aid in the follow-up of such patients. Objective: This study was conducted to determine the maternal plasma concentrations of cytokines in preeclampsia; and also determine their association with the severity of the disease. Design: An observational case-control study. Methodology: The study was conducted in 200 pregnant women, 100 with preeclampsia and 100 with normal pregnancy whose age, gestational age and parity were matched (control group) in the Department of Obstetrics and Gynaecology of Irrua Specialist Teaching Hospital, Irrua, Edo state. Peripheral venous blood samples were obtained and plasma levels of interleukin-6 and tumor necrosis factor were measured by an enzyme- linked immunosorbent assay kits (ELISA) obtained from Abcam, UK according to the manufacturer’s instruction.