Black hairy tongue (BHT) is a condition characterized by the elongation of filiform papillae associated with a marked discoloration, from yellowish-brown to black, and a thick lingual coating. BHT is usually observed in the elderly and in patients with limited self-sufficiency, as a consequence of poor oral hygiene. In this perspective, the patients affected by amyotrophic lateral sclerosis (ALS) represent a high-risk category for the occurrence of BHT. The fast and inexorable loss of their self-sufficiency due to progressive muscle atrophy as well as the impropriate education of healthcare assistants have demonstrated to have significant reflection on the maintenance of an adequate standard of oral hygiene. This paper firstly described a case of BHT in a patient affected by ALS. A case of BHT in a patient (Caucasic, male, 63 years old) affected by ALS was described. The primary goal of the work was to teach and motivate the patient to the use of the tongue cleaner in association with the local application of chlorexidine 0.20%. Furthermore, in order to support the patient with accurate domiciliary oral hygiene, a proper training for his health-care assistant was provided. The maintenance of the oral health of ALS patient is fundamental to prevent systemic complications that could jeopardize the already fragile physical balance of these patients. The dedicated monitoring by a dentist or a dental hygienist would seem essential in order to achieve this objective.