Dental hypersensitivity has been studied for several years and it is reported as a striking painful condition that originates from the exposition of dentinal tubuli as a result of the reduction of the thickness of the enamel or cement. Usually the exposed area is subjected to several kinds of stimuli, resulting in a rapid sharp acute pain. The aim of this study was evaluated the efficiency of LLLT in the treatment of patients with dental hypersensitivity. 1102 teeth of 388 patients from the Laser Center of the Camilo Castelo Branco University were treated with LLLT between 1995-2000. 98 males and 290 females aged 30 to 45 years old were treated. For LLLT, a diode laser was used at 780nm, CW, 40mW, elliptical area of the beam 2mm2, exposure time per point 25s. This corresponds to an equivalent dose of 50 J/cm2 at each point (considering the area of the spot). If a 1cm2 area is considered, the total dose per tooth is 4J/cm2. With the diode laser 830nm, CW, 50mW, elliptical area of the beam 2mm2, exposure time per po int of 20s. This corresponds to an equivalent dose of 50J/cm2 at each point (considering the area of the spot). If a 1cm2 area is considered, the total dose per tooth is 4J/cm2. The results showed 403 (36.57%) out of 1102 teeth required a single session for complete remission of the symptoms. 255 (23.14%) needed two sessions; 182 (16.51%) three sessions; 107 (9.7%) four sessions; and 59 (5.35%) five sessions. 96 (8.71%) did not respond to LLLT and the patients were re-assessed and treatment changed. The more affected tooth was the lower premolar (301 - 27.4%), followed by lower molars (163 - 14.8%), upper premolar (149 - 13.5%), and upper molars (52 - 4.7%), upper canine (119 - 10.7%), upper incisive (108 - 9.9%), lower canine (62 - 5.6%), and upper molars (52 - 4.7%). The result of the present investigation demonstrates indeed that LLLT, when based on the use of correct irradiation parameters, is effective in treating dentinal hypersensitivity as it quickly reduces pain and maintains a prolonged painless status. The authors concluded that the use of LLLT was effective on 91.27% of the cases. Previous studies were carried out by the authors to evaluate histologically the reaction of the dentinal pulp in rats after application of LLLT. The LLLT was shown to be efficient in the stimulation of odontoblast cells, producing reparative dentin and closing dentin tubuli.