Oral epithelial dysplasia refers to a premalignant lesion of the oral cavity. The diagnosis of dysplasia is rendered via pathologic assessment of diseased tissue. There are many different premalignant conditions identified in the oral cavity. These include leukoplakias, erythroplakias, proliferative verrucous leukoplakia, oral submucosal fibrosis, actinic cheilitis, and lichen planus. This article will discuss these different conditions and how they are diagnosed. It will also review the treatment for these entities.