According to data from the World Health Organization, cardiovascular diseases are the most common diseases of the 21st century. They are the reason for about 17 million deaths each year, including 9.4 million deaths caused by hypertensive disease or complications occurring during its course [http://www.thehealthwell.info/node/466541]. Therapeutic schemes in arterial hypertension include monotherapy or combination therapy involving administration of two or three drugs from various pharmacological groups, one of which should exhibit diuretic activity [Hypertension, 2003, 42, 1206–1252]. This review presents new information concerning analytical methods used in order to determine new substances of hypotensive activity belonging to two pharmacological groups, i.e., renin inhibitors and endothelin receptor antagonists.