Black hairy tongue (BHT) is an unusual condition in adults, and is characterised by marked accumulation of keratin on the filiform papillae of the dorsum of the tongue resulting in a hairlike appearance. The colour of the papillae may vary from brown to black. We describe a case of BHT in a 2-month-old infant. An extended review of the literature suggests that our case is the youngest ever reported. In conclusion, although BHT is considered benign, clinical, haematological and histological, evaluation is recommended to exclude several entities which can present as pigmented lesions of the oral mucosa.