Whenever endodontic therapy is performed on mandibular posterior teeth, damage to the inferior alveolar nerve or any of its branches is possible. Acute periapical infection in mandibular posterior teeth may also sometimes disturb the normal functioning of the inferior alveolar nerve. The most common clinical manifestation of these insults is the paresthesia of the inferior alveolar nerve or mental nerve paresthesia. Paresthesia usually manifests as burning, prickling, tingling, numbness, itching or any deviation from normal sensation. Altered sensation and pain in the involved areas may interfere with speaking, eating, drinking, shaving, tooth brushing and other events of social interaction which will have a disturbing impact on the patient. Paresthesia can be short term, long term or even permanent. The duration of the paresthesia depends upon the extent of the nerve damage or persistence of the etiology. Permanent paresthesia is the result of nerve trunk laceration or actual total nerve damage. Paresthesia must be treated as soon as diagnosed to have better treatment outcomes. The present paper describes a case of mental nerve paresthesia arising after the start of the endodontic therapy in left mandibular first molar which was managed successfully by conservative treatment.