PURPOSE: This study describes the CT findings of changes in the maxillary sinus after the Caldwell-Luc procedure. MATERIALS AND METHODS: The maxillary sinus-related findings in 35 cases among 20 patients(17 cases in 10 males and 18 cases in 10 females)who had undrgone the Caldwell-Luc procedure mean 14.6 years earlier were reviewed. CT scans were obtained in the axial and coronal planes, with 5mm thickness. By means of the t test, changes in the size of the bony wall of the maxillary sinus, as well as antral volume change, were compared with the normal maxillary sinus group(41 male and 23 female cases). Males and females were compared separately, and surgical bony defect of nasolabial antrotomy and nasoantral window, fibroosseous proliferation, compartmentation and mucosal thickening of the postoperative maxillary sinus were evaluated, as were findings of chronic or recurrent maxillary sinusitis and postoperative complications. RESULTS: Naso-labial antrotomy was clearly identified in 27 of 35 cases, and irregular bony surface in the remaining eight, as were 27 bony defects and one irregular bony margin among a total of 28 cases of nasoantral window. Due to shortening of the height of the orbit, reductions in maxillary width, nasoantral communication width and anteroposterior diameter of the maxilla, and widening of the width of the inferior meatus, the maxillary sinus tended to become hypoplastic and centripetally contracted. Reduced cavitary volume of the maxillary sinus was noted(p<0.05), and fibro-osseous proliferation(n=29), compartmentation(n=11), and mu-cosal thickening(n=22) of the postoperative maxillary sinus were also seen. There were findings of chronic si-nusitis(n=22), as well as complications of postoperative mucocele(n=3) and oroantral fistula(n=2) of the maxillary sinus. CONCLUSION: The characteristic maxillary sinus-related findings seen after the Caldwell-Luc procedure are helpful in distinguishing postoperative change from recurrent paranasal diseases and resulting complications.