Sinus lift surgery elevation is a procedure that requires radiological maxillary sinus evaluation and procedure planning. The condition of the maxillary sinus before and after sinus lift surgery was assessed. Sixty-five sinuses of 49 patients were included in the study. Preoperative and postoperative cone beam computed tomography (CBCT) scans were performed. The sinuses were analysed radiologically for pathological changes: mucosal thickening, ostia obstruction and accessory opening. The presence of concha bullosa in nasal cavity and septa in the maxillary sinus were recorded. The sinus volume also was measured before and after surgery. Thickened mucosa was found more often in postoperative scans than in preoperative scans (63.1% and 67.7%, respectively). Concha bullosa was found in 30 preoperative scans and in 33 postoperative scans. A correlation between mucosal thickening and ostia obstruction was found. The mean sinus volume decreased after surgery and the changes were statistically significant. In conclusion, changes of the maxillarysinus and nasal cavity can be detected with CBCT. Sinus lift surgery does not excacerebate the existing conditions of the maxillary sinus; however, there is a tendency for pathological features to increase after surgery. Sinus lift surgery is a safe surgery with regard to the maxillary sinus if performed with care.