The present study is meant to give an overview of the application of KTP lasers in endoscopic sinus surgery and to give an account of the experience gained in the course of 24 operations. Laser-assisted FESS was performed in 24 patients (13 on the right side and 11 on the left side). Sixteen men and eight women were treated for chronic maxillary sinusitis. Diagnostic criteria of chronic maxillary sinusitis included at least 3 months history of intermittent or persistent facial pain, intermittent or persistent fever, tenderness or headache over the areas of the maxillary, ethmoid or frontal sinuses, purulent discharge from nasal passages or nasopharynx, and radiographic evidence of opacification on CT scans. Traditional FESS surgery was performed on the one side and KTP laser-assisted surgery on the other side. CT was performed in each case. The operations were carried out under local anaesthesia. The KTP laser was delivered via an optical fibre (0.6 mm) and was used for bone ablation, incision, vaporization and coagulation. Patient symptoms were recorded using a self-administered questionnaire preoperatively, and postoperatively on weeks 1, 4, 12 and 24. Blood loss on the laser-assisted operations' side was minimal. The improvement of the symptoms (pain, sensation of fullness, discharge) during weeks 1 and 4 proved to be significant (P < 0.05) in the case of both techniques. The cumulated average of the point scores on the laser-assisted side was higher: especially postoperative week 1. Of the parameters assessed in the course of healing, oedema prevailed on the laser-assisted side, while crusting was characteristic in the traditional operation site. We conclude that laser-assisted FESS surgery is as effective as traditional endonasal sinus surgery. Its advantage is that it offers excellent haemostasis, as the use of 'star pulse' mode allows accurate bone work. No complications were observed. The disadvantage of the laser-assisted procedure is that the instrument is expensive and it is time consuming.