Malignant tumours of the nasal cavity and paranasal sinuses are uncommon amounting to 0.3-1% of all tumours and 3%-5% of carcinomas of the upper respiratory tract. Modern diagnostic techniques include endoscopy and computer tomography. Prognosis and therapy depend on the histological type, site of origin and extent of the tumour. The variety of possible treatment modalities demands individual therapy planning. A combined surgical and radiotherapeutic approach, possibly supplemented by small volume intracavitary brachytherapy or polychemotherapy in some defined histological tumour types, has been generally accepted, enabling a five year survival rate of 35%-45% to be achieved. The causes for failure are firstly local persistence of tumour (18%) or a local recurrence (37%). The cumulative recurrence rate after one and two years was 76% and 95% respectively. Late recurrences occur in 2.5% of cases. The complication rate with combined-modality therapy reaches 27% with minor complications occurring in 12% and major complications in 15% especially affecting the irradiated homolateral eye. The present statistical results show a number of weak points that cast doubt on their validity. We recommend a controlled, prospective, randomised, multi-centre and multi-disciplinary study to define the prognostic parameters for tumours of the paranasal sinuses and to choose the most effective, individually tailored therapy.