The authors evaluated the health of the maxillary sinus in a group of 18 patients who had undergone sinus lift surgery for implantation purposes, using computed tomography and endoscopic imaging as a means of diagnosis. The study was performed after a mean interval of 31 months. All sinus lift operations were carried out using the lateral flap technique. The authors evaluated graft characteristics and intraoperative and postoperative complications and compared the results with computed tomography and endoscopic images. Endoscopy of a maxillary sinus that underwent microlaceration of the mucosa during sinus lifting showed a situation compatible with healthy conditions. In cases complicated by macrolaceration, the endoscopic picture was typical of sinusitis, even where clinical conditions of this type were not present. In the absence of intraoperative complications, the endoscopic appearance of sinus mucosa appears to improve when autologous graft material is used.