Abstract The tongue is a complex organ involved in speech and expression as well as in gustation, mastication, and deglutition. The oral cavity, along with the tongue, are sites of neoplasms, reactive processes, and infections, and may be a harbinger of systemic diseases. This review inludes both common and rare diseases that occur on the tongue including: vascular and lymphatic lesions (infantile hemangiomas and oral varices), reactive and inflammatory processes (hairy tongue, pigmented fungiform papillae of the tongue, benign migratory glossitis, and fissured tongue), infections (oral hairy leukoplakia, herpes simplex and varicella zoster virus infections, human papilloma virus, and candidiasis), premalignant lesions (leukoplakia and erythroplakia), malignant lesions (squamous cell carcinoma, Kaposi sarcoma, and lymphoproliferative diseases), and signs of systemic disease (nutritional deficiency and systemic amyloidosis).