The study was performed on 103 human foetuses (58 female, 45 male) spontaneously aborted at between 14 and 30 weeks of gestation. The arteries were filled with latex, preserved in formalin and then dissected under the microscope and digitalised using a camera system. The following measurements were taken with the use of special computer software: the external diameter, the length and the volume of the arch of the aorta. The increase in diameter and length in relation to age corresponded to a linear function with values ranging from 1.77 mm to 4.09 mm for the diameter and from 4.94 mm to 13.31 mm for the length. The increase in volume corresponded to a square root function with values ranging from 13.42 mm3 to 173.96 mm3. Analysis of arch of the aorta variations revealed 11 cases of a common trunk for the brachiocephalic trunk and the left common carotid artery and 7 cases with the left vertebral artery arising directly from the arch of the aorta. In 2 cases the brachiocephalic trunk was absent, the right subclavian artery branching directly from the arch of the aorta at the level of the left subclavian artery or from the descending aorta just below the arterial duct ostium.