We investigated the effect of immune system in pregnancies complicated by pre-eclampsia on assessing umbilical cord serum levels of tumor necrosis factor- alpha.Thirty six babies born to mothers with pre-eclampsia, 22 of them were nulliparous composed the study group (group A). A comparison group was composed of 18 babies born to healthy mothers, 9 of them were nulliparous (group B).Mixed umbilical cord blood was collected immediately after delivery.Serum was prepared and all samples were assayed for (TNF-α) by specific enzyme linked immunoassays (ELISA).We found (TNF-α) level to be significantly lower in the umbilical cord serum of the pre-eclamptic patients [198 pg/ml ± 217 vs 72.75pg/ml ±135.23 pg/ml p value<0.05].Key word: pre-eclampsia, TNF-alpha.