Since 1978 (Lauritzen), several experimental and clinical procedures of end-in-end vascular microanastomosis have been described, including that proposed by Wang (1986) in which the tubulisation is accompanied by a counter-incision of the recipient vessel. Our experimental study was designed to assess the reliability of this procedure, to quantify it in relation to the diameter of the artery and direction of flow and to verify the existence of absence of any particular intraluminal histological phenomena. 42 Wistar rats were operated under general anaesthesia. 42 microanastomoses were performed: 15 carotid and 15 femoral in the direction of arterial blood flow, and 15 carotid anastomoses in the opposite direction to flow. The 15 carotid anastomoses performed in the direction of flow were all patent at each of the postoperative examinations (D0, D + 15, D + 90). Patency decreased in the anastomoses performed in the opposite direction to blood flow (10 out of 15 carotid anastomoses were patent) and as a function of the arterial diamenter (5 out of 12 femoral anastomoses were patent). Horizontal and transverse histological sections performed on the 15th and 90th days demonstrated continuity of the intimal endothelial lining and thickening of the adventitia of the two internalised and recipient walls in every case. In practice, although this experimental study demonstrates the clinical reliability of this internalised microanastomosis procedure in rat carotid arteries, the other results and the anatomo-clinical discrepancy do not justify its clinical use in all circumstances, particularly in the opposite direction to blood flow and in arteries with a diameter less than or equal to 1 mm.