Abstract Fifty subjects with varying degrees of dental deficiency were subjected to tests for masticatory performance, maximum force on all molars and premolars, food platform area, and were questioned as to food preferences. Complete dental examinations were made. Those persons who expressed a preference for tougher foods were found to have a greater maximum biting force than those preferring soft foods. The correlation coefficient between the two tests was 0.50 and was found to be statistically significant. The area for mastication rather than force that could be exerted was important in determining the deficiency in masticatory performance. The degree of deficiency was dependent upon the area lost rather than upon the type or number of teeth which were missing. Bone loss tended to reduce the maximum force which could be exerted. Other findings suggest that age and sex will have to be controlled in any further survey but do not indicate that fillings or extractions will affect the maximum force. Pain during mastication appears most important in determining which side will be favored in mastication. If pain is absent and there is a large difference in performance of the two half dentitions, persons usually will prefer the side on which mastication is best. When the two half dentitions are about equal in performance, the majority of persons prefer the right side. The side with greatest performance is usually the side with largest area, because these measurements are well correlated. The maximum force is apparently not a factor that influences the selection of side for mastication.