Background: Preeclampsia is a leading cause of maternal and fetal morbidity and mortality worldwide. Although its aetiopathogenesis is largely unknown, endothelial dysfunction may be a causative factor since cytokines are immune-regulatory substances that have been implicated in the pathogenesis of preeclampsia. Tumour necrosis factor α (TNF-α) is one of the proinflammatory substances that are thought to play a role in the pathogenesis of preeclampsia. Aim: To determine if there is a difference in the serum level of (TNF-α) in preeclamptic and normotensive pregnant women attending the antenatal clinic of the Lagos University Teaching Hospital. Methods: It was an analytical cross-sectional study of 45 preeclamptic and 45 normotensive pregnant women attending the antenatal clinic of the Lagos University Teaching Hospital, (LUTH), in their third trimester (between 28 and 40 weeks gestational age). Elevated blood pressure ≥140/90mmHg, proteinuria ≥ 3+, low platelet count, elevate or deranged liver function test and electrolyte urea, creatinine and uric acid level and clinical features were used as indicators of the severity of the disease. Blood samples were collected from the participants for analyses after obtaining informed written consent. Interviewer-administered questionnaires were used to obtain information from the clients. TNF α was determined using the Human Tumour Necrosis Factor α (TNF α, TNF) ELISA Kit. All data collected were subjected to statistical analysis using Stata version 13 Statistical Software for Windows.