Loss of sensation in the lower lip is a common symptom. Frequently, it can be ascribed to orosurgical procedures carried out in the region of the inferior alveolar nerve or its mental branch. Additionally, trauma, haematoma or acute infections may be the cause of the problem. Neoplasms, an excess of endodontic paste and some drugs are less frequently responsible. Three patients are described, in whom impaired sensation in the lip was the presenting symptom. In two of the cases, local factors were found to which this complaint could be ascribed. Further investigation, however, revealed that disease elsewhere was the underlying cause.