Introduction: Establishing a patient with a functioning AVF remains a challenge for vascular access surgeons. Presence of venous branches directing flow away from the main outflow vein in a brachiocephalic fistula may be one of the reasons for their failure to mature and often these are ligated. When not ligated 'retrograde flow' may occur and develop into an 'unorthodox' fistula. Case presentation: In Cardiff & Vale University Health Board, 331 brachiocephalic fistulas were created for haemodialysis access over a 3 year period. Five male patients were identified, with a median age of 69, who had, as a result of proximal cephalic vein stenosis/occlusion, developed a functioning mature fistula within a distal branch/forearm vein that eventually drains via the basilic vein. Moreover, the flow rates within these 'new' fistula outflow veins were comparable to functioning conventional brachiocephalic fistulas. Conclusion: These 'retrograde' brachiocephalic fistulas that have been inadvertently/accidentally created appear to be successful in providing stable vascular access for haemodialysis. These cases are an interesting find, as often such branches would have been ligated at time of fistula creation. When creating an AV fistula between the brachial artery and the median cubital vein consideration should be given to not ligating the below elbow cephalic vein.