Black hairy tongue is a benign clinical condition, usually asymptomatic and with an excellent prognosis. It is characterized by a black/brownish pigmentation of the filiform papillae of the lingual dorsum, which are hypertrophied. We describe a case of hairy tongue in a 65-year-old male, referred to the otorhinolaryngology consultation for presenting, with 1 month of evolution, notion of alteration of the tongue pigmentation, as well as complaints of oral discomfort and xerostomia. He was an active smoker of 42 pack-years and used a dental prosthesis. At the objective examination, the evident elongation of the filiform papillae of the posterior two thirds of the lingual dorsum, with black colour, hairy appearance and not detachable, was highlighted. The patient was advised to strengthen oral hygiene, combined with smoking cessation, as well as adjunctive oral nystatin. He was evaluated after 5 weeks of medical treatment and smoking cessation, with complete resolution of the hairy tongue. The diagnosis of black hairy tongue, as a clinical diagnosis, involves anamnesis and clinical examination of the oral cavity. Although the aetiology is not clear, multiple factors that predispose to its onset are known, the most frequent being smoking and alcohol, tea and coffee consumption. In the suspicion of black hairy tongue it is essential to explore the existence of any predisposing factors. In most cases, the avoidance of causative agents associated with an enhanced oral hygiene is sufficient to resolve this clinical condition. In the absence of clinical improvement, lingual biopsy and surgical treatment are indicated.