Interrupted and continuous microsuturing techniques were compared 3 weeks after microarteriorrhaphy in the rat femoral artery using light microscopy, and internal luminal diameter determinations were measured with a Bio Quant II Digitizer. The histologic appearance of the arteries of both groups was similar, with intimal hyperplasia, intimal incorporation of suture projections into the lumen, minimal inflammatory response to suture material, and restoration of the media. No significant difference was demonstrated between internal diameters at the anastomosis site for the continuous (N = 11, mean diameter 804 +/- 60 microns) and interrupted (N = 11, mean diameter 901 +/- 45 microns) groups. However, the experimental arteries in both continuous and interrupted groups were significantly dilated when compared to their controls (513 +/- 41 microns and 621 +/- 44 microns, respectively). This study indicated that interrupted and continuous suture techniques in laboratory microarteriorrhaphy result in similar histologic and morphologic characteristics, and that the repaired vessels were dilated compared to intact vessels.