The purpose of this investigation was to compare the masticatory muscle volume, bite force, and craniofacial morphology of migrainous subjects with age- and sex-matched controls. Ten adult dentate migraineurs were matched with 10 dentate age- and sex-matched controls. The groups consisted of nine women and one man (mean age, 43 years; range, 29 to 51 years). Volumetric analysis of the masseter and medial pterygoid muscles was performed using magnetic resonance imaging. Craniofacial morphology was analyzed from standard cephalometric radiographs using 30 angular and linear variables. Recordings of bite force were made using a strain gauge transducer. There was a significant difference in the volume of both masseter and medial pterygoid muscles between the two subject groups (P<.0001), with the muscles of the migraineurs nearly 70% larger. The migraineurs recorded significantly higher maximal bite forces (P<.0001) than did the controls. No significant differences for any craniofacial morphological measurement were demonstrated between the two groups. It was concluded that the migraineurs had larger masseter and medial pterygoid muscle volumes, and greater bite forces than the controls, which could not be explained by any change in craniofacial morphology.