Methods for studying efficiency and the results of studies using self-assessment and laboratory tests in subjects with various patterns of tooth loss are reviewed. It is concluded that age-related impairment of the dentition explains most of the decline in masticatory efficiency, while age per se has little influence. Many edentulous individuals are oral invalids and even when provided with optimal complete dentures their chewing efficiency is much lower than in those with natural teeth, with fixed prostheses on natural teeth, or with osseointegrated oral implants. The maintenance of a reasonable number of healthy natural teeth is the best guarantee for good masticatory efficiency with increasing age.