Background: Preeclampsia is characterized pregnancy-induced hypertension and proteinuria complicates 3 – 4% of pregnancies and thus is a leading cause of maternal and fetal morbidity and mortality. We aimed to assess the circulating IGF-I in the second trimester is associated with subsequent risk of preeclampsia. Subjects and methods: A case-control study included 60 women with preeclampsia and 30 normotensive women as control. All groups were strictly matched for gestational age at second trimester sampling of IGF-I levels, the IGF-I was measured with ELISA. Results: Diagnostic criteria for preeclampsia included blood pressure above 140/90 and proteinuria above 300mg. Mean ages of participants, gestational week, weight and BMI were similar. A decrease in IGF-I at second trimester was associated with higher risk of preeclampsia (P < 0.001). Conclusion: In pregnancies destined to develop PE, decrease of the circulating levels of IGF-I from the second trimester of pregnancy may be implicated in the pathogenesis of the disease.