Twenty-three cases with variations in the brachio-antebrachial arterial pattern of the human upper limb are reported. According to the artery which showed a variation, 4 groups were recognised: (1) isolated persistence of the median artery; (2) high origin of the ulnar artery; (3) high origin of the radial artery; and (4) duplication of the brachial artery, either with or without anastomosis at the cubital fossa. In addition, in groups 2, 3 and 4 the median artery may have persisted. Based on these arterial variations an anatomical and embryological correlation was established from a morphogenetic pattern which is proposed as being normal. Thus the terminal branches of the superficial brachial artery take part in the development of the radial, ulnar and median arteries, joining with the trunks of deep origin of these arteries in the primitive axial artery. Regression of the superficial arterial segments located proximal to this anastomosis gives rise to the definitive arterial pattern. Either the total or partial persistence of the superficial arterial segments explains those cases of high origin of either the radial or ulnar arteries as well as the duplications of the brachial artery. We postulate that the persistence of the median artery is independent of the presence or absence of any other variation in the arterial pattern.