Purpose: The purposes of this study were to: (1) compare dental hypersensitivity (DH) between hypomineralized permanent first molars and unaffected controls molars in patients with molar-incisor hypomineralization (MIH); and (2) assess the influence of opacity, color, and subject age on DH. Methods: This cross-sectional study identified 40 children/adolescents, who were attending a children's dental clinic and had one to three first permanent molars hypomineralized (demarcated opacities). The severity and color of the hypomineralized lesions were also evaluated. The assessment of DH was made using evaporative stimulus using a jet of compressed air applied by a dental syringe for one second, perpendicular to the occlusal surface employing the visual analogue scale (VAS) and the Schiff cold air sensitivity scale (SCASS). To verify the association between the presence or absence of DH and MIH, Pearson's chi-square and Fisher's exact test (P<0.05) were performed. Results: The frequency of DH was 28.0 percent in hypomineralized teeth and 9.4 percent in normal controls (by VAS; P=0.002). A higher frequency of opacities was observed (P<0.001). Older individuals had DH more frequently (P<0.05). Conclusions: Hypomineralized molars presented a higher frequency of dental hypersensitivity than control teeth, and dental hypersensitivity was associated with darker opacities of the lesion and older-aged subjects.