Purpose of Investigation: To evaluate placental growth factor as a screening test for gestational diabetes mellitus in the first trimester. Methods: Sixty-seven pregnant women who were admitted to the outpatient clinic of Ege University Obstetrics and Gynecology Department consecutively for first trimester bioanalysis between May 2005 and February 2006 were included in the study. The cohort of patients underwent 50 g or 100 g oral glucose tolerance tests at the 24(th) week of pregnancy. Placental growth factor levels were analyzed by ELISA (human PGIF, ELIZA kit, Quantikine, R&D systems, USA) from the maternal blood collected at the time of first trimester screening. Results: The study group of 15 patients with gestational diabetes were compared with a control group of 52 pregnant women with normal oral glucose tolerance tests. The level of placental growth factor was mean 35.79 +/- 16.79 pg/ml in the study group whereas it was mean 45,12 +/- 28.07 pg/ml in the control group. There was no significant difference between either group for placental growth factor maternal serum levels. Conclusion: Maternal placental growth factor serum levels are not useful in predicting gestational diabetes mellitus.