Background: Fetal growth restriction represents pathological inhibition of fetal growth and failure of the fetus to attain its growth potential. There is a strong association between stillbirth and fetal growth restriction. Objective: The aim of this study was to detect the relationship between Vitamin D deficiency in pregnancy and intrauterine growth restriction (IUGR). Patients and method: This case control study included a total of 56 pregnant women, attending for antenatal care at Department of Obstetrics and Gynecology, Faculty of Medicine, Maternity Hospital, Zagazig University. The included subjects were divided into two equal groups: Case Group (fetal growth restriction) and Control Group (healthy). Vitamin D level was measured at 35 weeks of gestational age by electrochemiluminescence technique. Result: All control group regularly consumed dairy products versus 78.6% within case group and 96% within control group versus 60.7% within case group receive calcium supplementation. regarding serum vitamin D level, it was significantly lower in case group than control group. Very severe vitamin D deficiency level (< 5 ng/ml) occurred in 10.7% within case group versus 3.6% in control group while sever vitamin D deficiency (5-10) occurred in 50% in case group and 35.7% in control group while suboptimal level (20-30) in 14.3% case group and 25% in control group, optimal level prevailed (30-50) in 3.6% and 14.3% within case and control groups respectively. The best cutoff value of serum vitamin D in prediction of IUGR was considered as <11.5ng/dl with area under curve 0.667, sensitivity 75%, specificity 53.6%, positive predictive value 61.8%, negative predictive value 68.2% and overall accuracy 64.3% (p<0.05). Conclusion: It could be concluded that vitamin D deficiency could be a risk factor for the occurrence of fetal growth restriction.