A new type of end-to-side anastomosis between small arteries is described. The anastomosis is made for three-quarters of its circumference with a nonoccluded recipient artery. The recipient artery must be occluded for only 3 to 5 minutes to complete the anastomosis. The anastomosis site was studied with the scanning electron microscope at different times (1 hour to 3 months) after the operation in 20 rats. In every case, the anastomosis was widely patent and a gradual endothelialization of the anastomosis site was observed. After 7 to 10 days, the endothelialization was more or less complete and, during the following weeks, a further smoothing of the ridge protruding into the anastomosis was noted. As an addendum, the authors describe an improvement of this technique that was developed after the sapphire tip of the neodymium: YAG laser became available. Now the anastomosis is fully completed and the connection between the two vessels is made by the laser tip introduced via a side branch of the donor vessel. The recipient artery need not be occluded at all. The results are promising.