The microhardness is an essential property of tooth enamel; there may be many factors that alter or diminish this quality causing weakness, one of which is dental fluorosis. The aim of this study was evaluate the surface microhardness of fluorotic enamel compared with healthy enamel. Two hundred forty extracted human molars were classified into four groups: Healthy (H), mild (MI), moderate (MO) and severe (S) fluorosis according to the Dean index. All samples were analyzed by Micro Vickers Hardness Tester. Average, standard deviation and ranges were calculated for quantitative variables, the ANOVA and Tukey test was used to identify differences between groups. The mean values of surface microhardness in HVN were: H, 333.4; MI, 290.3; MO, 266.1; S, 252.0. The differences between mean surface microhardness among healthy group and fluorotic groups were statistically significant (p