Studying health is a unique way of understanding how people adapted to changing socio-economic environments through time and skeletal health indicators or stress markers are often employed to measure how past populations adapted to their physical environment. Studying the skeletons of children allows a measure of population fitness, as the ability of a community to keep their younger inhabitants alive and in general good health attest their ability to adapt to their environment. In this study, skeletal remains of children from infancy to adolescents from a number of early medieval (400-1169 AD), later medieval (1169-1540 AD) and post-medieval (1540-1700 AD) sites from around Ireland were assessed in order to investigate health of Irish children during these periods. Based on pooled data from 26 sites, totally 2,074 skeletons. The material was derived from published and unpublished works by a wide variety of authors completed over many years. In this study a number of non-specific indicators of physiological stress such as cribra orbitalia, porotic hyperostosis, dental hypoplasia, and periosteal new bone formation were considered in order to gives clues as to the state of health and likely illnesses encountered by medieval Irish children. Keywords: health; past populations, Ireland, nutritional deficiencies, diet