Changes in functional jaw movements during a 2-year period of denture wear were investigated. The sample consisted of 27 partially edentulous subjects who were provided with an immediate complete maxillary denture and a removable partial mandibular denture. Recordings of habitual chewing of apple and empty open-close cycles were made with a mandibular kinesiograph. At the pretreatment stage, when the patients occluded on a residual anterior dentition, irregular patterns of movement were observed. After placement of the dentures, which restored posterior occlusion, the chewing and open-close patterns showed marked improvement and were characterized by significant mean decreases in sagittal and transversal range of movement. Relining of the maxillary dentures further stabilized the functional patterns. During the second year, significant reductions in vertical range of movement and lateral chewing excursions were observed, and were probably related to impaired retention of the complete upper denture.