SUMMARY:The aim of this study was to evaluate the effects of maternal protein and energy restriction during lactation on mandible dimensions of pups (female) at aging. At parturition, Wistar rat dams were randomly assigned to the following groups: 1) control group (C) -free access to a standard laboratory diet containing 23% protein, 2) protein-energy restricted group (PER) -free access to an isoenergetic, protein-restricted diet containing 8% protein, and 3) energy-restricted group (ER) -fed with restricted amounts of a standard laboratory diet. At weaning (d21), all pups were separated of dams and received free access to a standard laboratory diet containing 23% protein until 90 days (d90), when the rats were anesthetized and sacrificed. The dimensions of excised pup mandible were measured directly using pre-established 3 anatomical points. Morphometric analysis showed that most of the measurements in the ER and PER groups were significantly lower than in the control group, with the greatest reductions occurring in the PER group. These results show that protein and energy restriction during lactation have an important influence on pup mandible development and continue through the aging process.