OBJECTIVE To evaluate the histologic effects and permeability rate of different suture materials in microsurgical anastomosis of the left uterine horn in Wistar rats. METHODS In this histologic study, 81 female Wistar rats were used. A transverse section and anastomosis were performed using three surgical techniques. The rats were divided into 15 experimental groups based on evaluation of three variations in microsurgical technique: (1) one-layer transmucosal anastomosis, (2) one-layer extramucosal anastomosis, and (3) two-layer transmucosal anastomosis. With each technique, five suture materials were used: 7/0 polyglycolic acid, 6/0 polyglactin, 7/0 polydioxanone, 7/0 silk and 7/0 polypropylene. RESULTS The permeability rate was 86%. Polydioxanone persisted in 41% of cases at 90 days. Abnormal proliferation of mucosal epithelium was verified in 10% of cases. Polypropylene was responsible for the majority of foreign-body granulomas. Polydioxanone produced the smallest inflammatory reaction. CONCLUSIONS The type of suture material did not influence the permeability rate. Use of nonabsorbable suture material altered the histologic structure the most and produced the greatest tissue reaction. The best results were obtained with polydioxanone. Monofilial sutures gave rise to fewer structural alterations than did multifilament sutures.