Purpose:The aim of this study was to compare the effect of Nd:YAG laser to that of a new varnish: MI Varnish with RECALDENT (GC), for the treatment of dentin hypersensitivity, with a follow-up of 6 months. Dentinal hypersensitivity was evaluated using a new thermal test never before used on dental tissue. Materials and Methods: A split-mouth design was used where teeth on one side received the same type of treatment. Twelve patients suffering from dentin hypersensitivity were chosen. Fifty-four teeth were divided into 27 pairs. Twenty-seven teeth received the Nd:YAG laser treatment, and the 27 contralateral teeth received MI Varnish application. Five parameters were measured, and the measurements were taken before treatment at baseline (T0), after 1 week (T1), 1 month (T2), 3 months (T3), and 6 months (T4) of the application. Air stimulation to obtain the Schiff air score, the score of discomfort according to the visual analog scale (VAS), the tactile score, and the thermal test that determines the minimum cold-stimulating temperature and the maximum heat-stimulating temperature were all used to assess sensitivity. Statistical analyses of the data were performed, and the significance level was set at p ࣘ 0.05. Exact Fisher tests and Chi-Square tests were conducted to compare percentages. Results: There was a clear decrease in dentin hypersensitivity for both treatments (Nd:YAG laser and MI Varnish) especially between baseline and 1 week, with maintenance of this state through the 6-month follow-up period. The difference between the two treatments was not significant, comparing, over time, the Schiff air score, the thermal test, and the VAS; however, the tactile score was significantly improved 6 months after the application of MI Varnish compared to the laser (p = 0.05). Conclusion: There was no significant difference between the two treatments, Nd:YAG laser and MI Varnish. Both treatments were effective and reduced dentin hypersensitivity immediately after treatment up to 6 months.