Apelin, a novel multifunctional peptide implicated in the regulation of the cardiovascular system, including blood pressure and cardiac function control, has been postulated to be involved in the pathophysiology of hypertension and hypertensive heart disease. The aim of this study was to investigate, for the first time, whether the effects of apelin's chronic application might be involved in deoxycorticosterone acetate-salt-induced hypertensive rats (DOCA-salt rats). In this study, 8-10-week-old male Wistar rats were divided into four groups: control, control + apelin, DOCA-salt rats, DOCA-salt rats + apelin. Deoxycorticosterone Acetate (25 mg/kg of body weight) was injected subcutaneously, twice a week for 4 weeks. These rats received NaCl 1% instead of tap water for drinking during the experimental period. Later, rats were randomly treated with pyroglutamylated apelin-13 (200 mu g.kg(-1). day(-1) intraperitonealy) for 17 days. The concentrations of apelin, endothelin-1, angiotensin-converting enzyme, angiotensinogen, and angiotensin II were analyzed in the plasma. The mRNA level of apelin and apelin receptor were determined in the heart and aorta tissue by real-time polymerase chain reaction, respectively. It was found that apelin reduces blood pressure in DOCA-salt rats. Apelin can be used as a therapeutic agent in the treatment of hypertension in the future.