The constant search for the ideal restorative material causes the new formulations to aim for an increase of 4 to 5 mm, getting an improvement of its mechanical properties, for example, the organic and inorganic matrix of other materials. With this, the objective of the present study was to evaluate the microhardness of different brands of bulk fill resin. In order to perform the research, 30 specimens were prepared, with group 1 with 10 specimens of the conventional composite resin Opallis (FGM). Group 2 with 10 specimens of Oppus Bulk Fill composite resin (FGM). And group 3 with 10 specimens of the Tetric N-Ceram Bulk fill resin (Ivoclar Vivadent), all made from a preset silicon matrix. Each group was photopolymerized on the upper surface at the time indicated by the manufacturer, stored in an oven with distilled water under 37 ° C for 24 hours. After this period, they were measured with a digital caliper and submitted to the Vickers microhardness test at 5 random points on the upper surface. The values recorded by the microdurometer were taken to the statistical analysis using ANOVA test with Tukey post-test, in which it showed a statistical difference between Bulk fill Tetric N-Ceram (Ivoclar Vivadent) and Opallis (FGM) with p value<0.001, and a statistical difference between Bulk Fill Tetric N-Ceram (Ivoclar Vivadent) and Opus Bulk Fill (FGM) with a p value of 0.001. There was no difference between Opallis and Opus Bulk fill (FGM). It was concluded that Bulk Fill Tetric N- Ceram resin (Ivoclar Vivadent) obtained a lower microhardness when compared to Opallis (FGM) and Opus Bulk Fill (FGM) resins.