There are different opinions concerning the benefits of oblique anastomosis and stripping of the adventitia before microvascular anastomosis. For clarification of this question, microvascular anastomoses by different techniques were performed in the aortas and the femoral arteries of 80 female Wistar rats. The average diameter of the aortas in these rats was 1.4 mm, and the average diameter of the femoral arteries was 0.7 mm. The following procedures were carried out: transverse division of the vessel and end-to-end anastomosis; transverse division of the vessel with adventitial stripping of the ends before end-to-end anastomosis; oblique division of the vessel and end-to-end anastomosis; oblique division of the vessel with adventitial stripping before anastomosis. Forty of the animals were sacrificed after 5 hours, and the remaining 40 animals were sacrificed after 3 weeks, and histologic studies were performed. All anastomoses performed on the aorta were patent at the 5-hour follow-up. The 3-week follow-up showed no differences between the transverse anastomoses both with and without adventitial stripping, but there was an accumulation of false aneurysms in the groups with oblique anastomoses and adventitial stripping. In the animals that received femoral artery anastomoses, 80% of the transverse anastomoses without adventitial stripping were patent after 5 hours of 3 weeks. The animals that received oblique anastomoses without stripping had patent vessels after 3 weeks, but there was a significant accumulation of false aneurysms in the two groups that received adventitial stripping. As this study demonstrates, the patency rate of microvascular anastomoses in vessels less than 1 mm in diameter cannot be improved significantly by oblique division with or without adventitial stripping. In addition, adventitial stripping was followed by a high percentage of false aneurysms.