One hundred and fifty-five patients with complaints indicating acute sinusitis were examined and their symptoms and signs registered. The final diagnosis--maxillary sinus empyema versus not empyema--was established by means of antral aspiration. A computer-based analysis of clinical data demonstrated the significance of the clinical examination. Local symptoms such as pain and purulent rhinorrhea with unilateral predominance were particularly guiding, even in bilateral cases, while nasal obstruction, tenderness during percussion, and affected general condition were not. With an overall reliability of about 85%, appropriate therapy can be suggested based on the clinical findings alone.