Background: Preeclampsia is the most frequent medical complication of pregnancy and it is a multisystem disorder. Previous studies suggested a relationship between thyroid hormones levels and preeclampsia. Objective: To assess the relation of thyroid hormone and preeclampsia. Method: This was a case-control study conducted at the Department of OBG, Babylon Teaching hospital for Maternity and child complex from the 1st of Jan 2018 to the end of May 2018. Results: Total 200 respondents were included in this study, thyroid stimulating hormone TSH was increased in preeclamptic patients and were more than the other with significant association (p=0.02). T3 was decreased significantly in preeclampsia than normal healthy women with a decrease from severe to mild (0.04). Thyroid hormone T4 was also decreased in preeclamptic pregnant women than normal pregnant but no significant association was found (p=0.06). Conclusion: There is a significant relation between preeclampsia and thyroid hormone.