The objectives of this study were to provide a quantitative account of the extent to which the maxillary complete denture moves during function (chewing, swallowing, and speech production) and to determine whether differences in movement occur as a function of denture fit. A total of 24 patients were studied, 12 with poorly fitting dentures and 12 with well-fitting dentures. Denture movements were measured with a Myotronics kinesiograph that tracked the movements of a small magnet attached to the inferior surface of the denture. Results indicated that denture movement was greatest for the two chewing activities; varied extensively from individual to individual; and that there were no statistically significant overall movement effects as a function of fit. It was concluded that all maxillary dentures are subject to movements in all directions, but that the degree of movement is related more to the individual denture wearer than it is to the fit of the denture.