CT scans from 100 patients undergoing endoscopic sinus surgery (ESS) were primarily re-examined in order to assess the quality of the radiological examinations and the information it could provide years later. The material comprised the cases of patients who had undergone ESS by one surgeon (AD) in the 1990s. The indications for surgery were acute recurrent or chronic sinus infections, polyposis of the nasal and paranasal cavities, mucoceles and sinogenic headache. All examinations were described using a scheme modified according to Stoney et al., evaluating the opacity/mucosal thickening, drainage/pathways, the lateral nasal walls, septum and other bony walls. This study has been re-evaluated and an additional group of 20 patients consecutively operated on in 2002/2003 has been added. The initial radiological examinations often proved incomplete, with insufficient descriptions of either the drainage/pathways, the lateral nasal wall or the septum and bony walls, which all are structures of great value to evaluate preoperatively for the endoscopic surgeon. The operative findings correlated well with the CT if taken between 4-6 weeks before the operation. The structural pathology correlated with preoperative endoscopic findings independently of the time lapse between the scans taken and the date of surgery. The development and the gradual implementation of the picture archiving and communication system (PACS) certainly represent huge advantages in radiological assessment. The need for CT scans to be available in the operating room calls for specific computer installations to make PACS readily available peroperatively and in an easily workable way for the surgeon.