Nowadays stress represents one of the greatest threats to the homeostasis and by that to human health in general. When under stress, an organism initiates defense mechanisms to maintain the necessary balance and resist the harmful effects from the environment. The main role in that process hold the autonomic nerve system and the endocrine system, coherence of which provides the required protection to the organisms. Stress response is regulated by the CRH, ACTH and glucocorticoids which are all secreted by the hypothalamus-pituitary-adrenal axis. Response or the way that the body handles the stress depends largely on its resilience. It represents the capability of an organism to adjust to trauma and cope with chronic difficulties. Except for being genetically conditioned and depending on the concentration of key neurotransmitters, its important component is also represented by psychosocial factors and emotional capability to cope with stress. However, an important aspect in mechanisms which protect the body from stress is also the oldness of an organism. Although it is too early to see the visible consequences of stress during the prenatal period, the chronic exposure to high concentrations of glucocorticoids in early childhood shows harmful consequences to organism in adolescence, adulthood or old age. It is therefore evident that chronic stress exposure in any life period leads to unwanted effects later in life.