Background: Many studies examined the usefulness of foramen magnum (FM) parameters for sex and age prediction. The aim of the current study is to assess the possibility of using FM shape and size for sex and age prediction in a sample of Upper Egypt population. Methods: The study analyzed cranial CT (computed tomography) scans of 150 individuals (75 males and 75 females), aged <1 to 28. The scans were selected from the PACS (Picture archiving and communication system) database at Sohag University Hospital, Egypt. FM shape was visually examined, and anteroposterior diameter (APD) and transverse diameter (TD) were measured, followed by the calculation of FM index (FMI) and area using the Radinsky formula (area-R) and Teixeira formula (area-T). Results: The study found that the most frequent shapes were hexagonal in females and oval in males. Irregular "a" shape was the most common in the children’s group. Age and sex significantly influenced FM shape. Regarding FM measurements, the children’s group had statistically lower mean values than the adolescents’ and adults’ groups. There was a positive correlation between FM measurements and age in children. Linear regression analysis was used to predict age from FM parameters using regression equations. Males exhibited higher FM measurements than females in the adults’ group; however, the difference was significant only for TD and FMI. Binary logistic regression indicated that TD could predict sex in the adults’ group with a 64% accuracy rate, with higher accuracy for the female sex. Conclusion: FM morphology and morphometry can help determine age in early childhood and sex in adulthood. Key words Foramen magnum, morphology, morphometry, age, sexual dimorphism, CT Introduction ne of the most important areas of forensic inquiry is personal identification. Age and sex identification are vital in cases involving unidentified individuals, skeletal remains, and mutilated bodies, such as those resulting from bombings and disasters (Lashin et al., 2019). The skull base holds particular value in identification, as it is more resilient to physical trauma and burial than other parts of the cranium (Jain et al., 2013). One of the key features of the skull base is the foramen magnum (FM), the largest opening in the skull base, which transmits the medulla oblongata and other critical structures (Yilma et al., 2020). As a part of the skull, the size and shape of the FM change with the growth of skull bones. During early life—from the 7th intrauterine month until birth—the anteroposterior diameter (APD) of the FM expands faster than the transverse diameter (TD) by 5.4%. After birth and up to six months of age, the TD grows faster than the APD by 6.7%. The growth of the APD typically stops by the age of five, while the TD continues to grow until around the age of ten (Zdilla et al., 2017). F