Angiotensin II (Ang II) is an important stress hormone. Circulating and tissue Ang II are significantly increased in both acutely and chronically stressed animals. In humans, the plasma Ang II content increases markedly after sprinting, as does Cortisol. The present paper reviews recent studies with special reference to the correlation between the renin-angiotensin system (RAS) and the hypothalamus-pituitary-adrenal cortex system and sympathetic-adrenal medulla system during stress. We would like to suggest that in the stress response, Ang II is not only a stress hormone to various peripheral organs, but is also a notable factor in initiating the systemic stress response from central to peripheral tissues. The RAS is therefore a stress hormone response system similar to the hypothalamus-pituitary-adrenal cortex system and the sympathetic-adrenal medulla system.