A 55-year-old male patient with chronic hepatitis B was started on tenofovir. One month after initiating the new medication, he developed severe symptomatology with odynophagia and a very painful tongue. The physical examination reveals multiple erythematous patches on his tongue and a biopsy was performed. It allowed the diagnosis of benign migratory glossitis or geographic tongue. The patient was kept on tenofovir, but had to start topical corticoid therapy. Geographic tongue is a common condition that may be caused by drug idiosyncrasy, but has never before been associated to tenofovir. It is usually asymptomatic, but sometimes it causes severe symptoms, being an important impairment of quality of life.