Conclusion. The common association between adult-onset otitis media with effusion (AO-OME) and squamous cell metaplasia (SCM) of the epithelium of Rosenmuller's fossa, which is near the Eustachian tube orifice, implies the predictive role of metaplasia, which probably compromises the drainage function of the middle ear. Objective. To determine the effects of nasopharyngeal epithelial changes (SCM) on AO-OME. AO-OME is a multifactorial and insidious disease that may necessitate detailed investigation, i.e. biopsy of the nasopharynx, because of possible underlying nasopharyngeal malignancy. Material and methods. Fifty-two patients with AO-OME ( study group) and 29 with a unilateral neck mass in the posterior triangle without AO-OME ( control group) were enrolled. Nasopharyngeal biopsies taken from all subjects were evaluated with regard to surface epithelial changes of the nasopharynx. Results. Nasopharyngeal biopsies revealed SCM in 34/52 patients (65%) in the study group and 9/29 (31%) in the control group (p< 0.05). During the follow-up period, recurrence of effusion occurred in 56% of the group with SCM and 22% of the group without it.