Er,Cr:YSGG laser is a rising treatment option for dentine hypersensitivity (DH). However, there is no data available concerning the scanning electron microscope (SEM) evaluation of the clinical application of Er,Cr:YSGG laser in the treatment of DH. The aim of this study was to evaluate and compare the desensitising and tubule occlusion effects of Er,Cr:YSGG laser with different power settings. Twenty patients (60 teeth) participated in this study. For each patient, teeth were randomised to 3 groups. In groups 1 and 2, patients were treated with Er,Cr:YSGG laser at 0 center dot 25 and 0 center dot 5W, respectively. In control group, same laser was applied without laser emission. DH was assessed for all groups with a visual analogue scale (VAS). When compared with the baseline data and control group, in both active treatment groups laser irradiation provided a desensitising effect immediately after treatment (P<0 center dot 001). In group 2, VAS scores were significantly lower than group 1. The tubule diameters in the both laser groups were significantly smaller than the control group (P<0 center dot 01). When group 1 compared with group 2, group 2 showed significantly smaller tubule diameters (P<0 center dot 001). Both 0 center dot 25 and 0 center dot 5W laser irradiation were effective for the treatment of DH; however, 0 center dot 5W laser irradiation showed best results for the decrease in VAS scores. The SEM findings of the reduction in number/patency of dentine tubules seem to be related to the clinical findings, which were associated with improvement in treatment efficacy.