Abstract: Apelin is a new multi - functional peptide that has already been linked to blood pressure and cardiac function modulation. It's hypothesised to play a role in hypertension and hypertensive heart disease development., Nitric oxide (NO) was recognized as an endogenous signaling molecule that modulates vascular compliance and organ perfusion via its powerful vasodilatory effects, hypertension, atherosclerosis, and chronic renal problems, are hypothesized to limit NO bioavailability, leading to disease progression. Our study aimed to know the role of apelin and nitric oxide in the pathogenesis of essential hypertension and correlate the levels of apelin to nitric oxide in both genders, A total number of 90 participants (70 hypertensive patients and 20 control) were enrolled, all participants underwent blood pressure, serum apelin and NO measurement, our results revealed decreased serum apelin levels in essential hypertensive patients, while serum NO was increased compared to controls with no significant gender difference..