Adrenomedullin is a vasodilative peptide found in 1993. It has been proved that proadrenomedullin can be divided into 4 peptides by endoenzyme. Proadrenomedullin N terminal 20 peptide (PAMP) is one of them. PAMP has many functions on cardiovascular physiology. But so far the relationship between PAMP and cardiovascular diseases has not been found. In this study its plasma levels in the patients with essential hypertension(EH) and heart failure(HF) were investigated with its pathophysiological effect discussed. The plasma levels of PAMP, endothilin(ET), Angiotension II(AT II) were measured with RIA, and norepinephrine(NE), epinephrine(E) were measured with HPLC. the plasma level of PAMP in the control group was 18 42?2 33ng/L, and was 1 62 times higher in EH group than in the control group, and was 1 53 times higher in HF group as compared with the control group respectively ( P