The preoperative roentgenmorphology of the nasomaxillary sinuses was compared with the intraoperative findings. The dates of 285 patients were evaluated. For the maxillary sinus there was correspondency in 85.7%. There were no differences in the cases explored with tomography. For the ethmoidal sinus there was correspondency in 89.5% and for the frontal sinus in 82.7%. The importance of the preoperative roentgenexamination with the standard exposure in occipitomental projection was less the demonstration of the inflammation than of other findings. The sphenoidal sinus was best explored by tomography. The standard projection did not always allow the differentiation of cysts, polyps and mucoceles in diseased sinuses. The tomography was superior to the standard projection, in tumor patients the accompanying inflammation could not be separated from tumor infiltration with certainty.