Numb chin syndrome reflects an abnormality in the mental nerve or inferior alveolar nerve, or occasionally in a nervous structure located higher up in the body. It manifests as objective and/or subjective sensory disorders in the distribution of the mental nerve or inferior alveolar nerve, represented primarily by half of the lower lip and chin. Although numb chin syndrome falls mainly within the province of dentists and stomatologists, it can reveal a number of neoplastic or other diseases seen by rheumatologists. This article provides background information on numb chin syndrome, discusses its causes (including those seen mainly by dentists and stomatologists), and reviews numb chin syndrome due to generalized malignancies based on 144 cases from the literature and two personal cases.