Chloroform is used widely in endodontic treatments for solving gutta-percha points, but it can have destructive effects if it comes in to contact with oral mucosa. This article presents a case of necrotic ulcer of palatal and buccal mucosa due to injudicious use of chloroform in endodontic treatment, which has caused severe destruction in maxilla. A conservative treatment method of repeated curettage and irrigation was used and although the lesion healed completely, it had major effects on the patient's quality of life including loss of two teeth. It is important that dentist be aware of the devastating effects of imprudent application of various chemicals used in dentistry. The conservative treatment used for this case can be helpful option for similar cases.