Child is a being and provides the genetic continuity of parents and society, and therefore the fitness of these children for survival, growth and development towards reproduction, is of significance to parents and society. The aim of health care for high-risk children is not only to minimize or eliminate health problems, but also to optimize their fitness. Considering that the health care of children is influenced by available resources of parents and society, and sociocultural values and paradigms in a given environment of evolutionary adaptedness (EEA), child health care professionals need to understand factors affecting the optimal fitness of children with risks. This paper introduces a new integrated theory for health care in high-risk children, entitled, Health for Optimal Fitness of High-Risk Children. Five main components were identified with associate concepts or midrange theories affecting heath for optimal fitness of high-risk children; EEA, optimal fitness, health problems, investment resources, and anthropological values. It may provide an integrated perspective on health of high-risk children in both the proximately biomedical approach and ultimately evolutionary approach as optimizing their fitness. Further study is needed to develop substantial statements between components with existential examples.