BACKGROUND:Diagnosis of epithelial dysplasia has traditionally been subjective, and there is a need for a quantifiable and useful test. METHODS:In a double blind study, clinical leukoplakias from 52 people were diagnosed for presence (DLK) or absence (NDLK) of epithelial dysplasia using hematoxylin and eosin (H&E) stain as a gold standard criterion, and results were compared against their mean silver stainable nucleolar organizer region (AgNOR) counts. We used mean AgNOR count cut-point of 2.37 from our prior report as the diagnostic threshold (mean >or= 2.37 being DLK and mean < 2.37 being NDLK). RESULTS:The two methods (H&E and AgNOR) disagreed in 37% of the diagnoses. Both NDLK and DLK had high AgNOR counts. P-AgNOR was non-contributory for diagnosing epithelial dysplasia. CONCLUSIONS:Mean AgNOR count can be a useful tool in definitive diagnosis of epithelial dysplasia.