The study was conducted to define a normal range for the length, external diameter and volume of the brachiobicarotid trunk during gestation. The material examined consisted of 128 human fetuses of both sexes (63 male, 65 female) aged from 15 to 34 weeks, from spontaneous abortions or stillbirths. The arterial bed was filled with white Latex LBS 3060, specimens were fixed in a 10% formalin, and then branches of the aortic arch were dissected, recorded using a camera, and digitalized to JPEG images. Afterwards, the brachiobicarotid trunks underwent morphometric analysis with the digital image analysis system of Leica QWin Pro16. Regression analysis was used to investigate the growth of the brachiobicarotid trunk during gestation. The brachiobicarotid trunk was observed in 27 of the 128 fetuses studied (21.09%). The results showed the brachiobicarotid trunk length as a function of fetal age, which could be expressed by y = -1.250+0.1433x+/- 0.7682, and the brachiobicarotid trunk diameter by y = -3.034+0.2845+/-0.4253. The volumetric growth of the brachiobicarotid trunk followed the quadratic function y = 178.5-19.69x+0.545x2+/-20.112. The correlation coefficients between arterial length or external diameter and fetal age, and the coefficient of determination between arterial volume and fetal age were as follows: r = 0.76 for length, r = 0.97 for external diameter, and R2 = 0.84 for volume (P<0.001). The relative diameter of the brachiobicarotid trunk increased from 0.738+/-0.089 to 0.916+/-0.088 during the study period.