Background: A recently discovered measurement called transverse cerebellar diameter (TCD) is used to estimate a fetus's gestational age (GA). When determining GA, the measurement of TCD is incredibly accurate, especially when the last menstrual period (LMP) date is uncertain. Objective: This study aimed to assess the diagnostic accuracy of fetal TCD as independent parameter in diagnosis of intrauterine growth restriction (IUGR). Patients and methods: This prospective observatory study was conducted in Obstetrics and Gynecology Department, Menoufia University Hospital and Berket El-Sabaa Central Hospital through the period from November 2022 to February 2024. 200 pregnant women attended to Antenatal Care Outpatient Clinic for follow up with a mean age of 26.43 ± 6.115 years old, singleton pregnancy, GA more than 13 weeks and clinically suspected intra uterine fetal growth restriction (FGR) were enrolled. Results: The study included individuals with a mean parity of 1.47 ± 1.5, a mean BMI of 26.32 ± 5.028 kg/m², and 19% of patients were obese. There was a highly statistically significant lower mean value of GA by TCD in IUGR was 27.18 ± 7.454 compared to Non-IUGR that was 34.95 ± 3.502 (p < 0.001). Conclusion: TCD is a critical measure for identifying IUGR and appropriately measuring GA. This is especially crucial for patients who arrived at the hospital without any medical records or prior prenatal care visits, particularly those from low-income families. These individuals frequently do not recall their LMP or estimated date of delivery (EDD), making it difficult for clinicians to precisely determine the GA of the fetus, especially in situations of IUGR.