The maxillary sinuses of 40 patients suffering from primary atrophic rhinitis (ozaena) were studied radiologically, antroscopically and histopathologically. Sixty per cent of the patients showed thick bony walls and a small cavity of the maxillary sinus on X-ray and on antroscopy. On the other hand, 25 per cent of the cases revealed signs of infection including mucopurulent secretion on antroscopy associated with corresponding histopathological changes. It is concluded that poor pneumatization of the antrum plays a more important role in the pathogenesis of ozaena than infection.