Background: Few studies evaluated cavum septum pellucidum (CSP) and cor-pus callosum (CC) indices in late gestation. This study assessed CSP and CC indices, along with frontal lobe measurements, and examined correlations among parameters. Methods: A cross-sectional study was conducted at Imam Khomeini Hospital Complex on 150 fetuses at ≥36 weeks’ gestation. Transabdominal ultrasound was used to measure CSP length, width, trace length, and area in the axial view; frontal lobe thickness from anterior and posterior CSP margins in horizontal and vertical directions; and CC lengths and thicknesses. CSP trace length and area were also obtained in the midsagittal view. Data were analyzed using SPSS 23. Results: Mean gestational age, biparietal diameter (BPD), head circumference (HC), and estimated fetal weight (EFW) were 37.56±1.08 weeks, 90.73±3.20 mm, 326.58± 10.59 mm, and 2987.82±333.68 gr. In the trans-thalamic view, median CSP length, width, trace length, and area were 8.92 mm, 6.05 mm, 2.81 mm, and 0.49 mm². Median CSP height in the coronal view was 5.85 mm. In the midsagittal view, mean CC outer-to-outer length, inner-to-inner length, CSP trace length, and CSP area were 41.31±4.81 mm, 29.73±4.17 mm, 2.56±0.63 mm, and 0.36±0.19 mm². All CC and CSP indices correlated significantly with HC (p<0.05). Frontal bone–to–CSP anterior and posterior distances in axial and near-field views also correlated with HC (p=0.0001). Conclusion: This study provides normative measurements for CC, CSP, and frontal lobe indices at ≥36 weeks’ gestation. These values support late-gestation brain assessment and early identification of newborns potentially at risk for neurodevelopmental concerns.