A different approach to end in end anastomosis was tested to minimise the undesirable traits of classic and sleeve (telescoping) methods. Our approach aimed to maintain full contact at the level of the anastomosis by using longitudinal matrix sutures as a new invaginating suture technique in microarterial sleeve anastomosis. Classic end-to-end anastomosis with seven to eight stitches, Lauritzen's end-in-end anastomosis with four stitches, and our modified end-in-end anastomosis with two horizontal matrix sutures were made in 10, 20, and 25 rat femoral arteries, respectively. Nine, 17, and 18, respectively were patent at early evaluation; and eight, 13, and 14 at the time of late evaluation. There was no significant difference in between the patency rates of the groups. Histopathological examination showed large strictures and the formation of intra-luminal organised thrombus with thin intramural fibrin precipitation in occluded specimens. The longitudinal matrix sutures in the sleeve anastomoses, which passed through all layers of the vascular wall, injured the intima (a vertical rupture) and constricted the lumen.