Mucosal biopsies were taken from the anterior mesotympanum in four patients with OME and another four patients with CSOM. There was no significant abnormality of cellular surface structure in patients with chronic middle ear disease. Furthermore, no significant difference was observed between smoke exposed and nonsmoke exposed patients. It is concluded that the effect of tobacco smoke on CBF is functional and not related to any anatomical abnormality observed by scanning electron microscopy (SEM).