Angiotensin II is a potent vasoconstrictor that stimulates aldosterone secretion. Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are currently in use for the treatment of hypertension and chronic heart failure. Clinical trials show ACEIs to be effective, but with significant side effects, while ARBs provide a useful, more well-tolerated, alternative. ARBs are based on the structure of losartan, and efficacy has been enhanced by development of longer-lasting insurmountable antagonists. Combination therapy is another option; however, there is also scope for development of new molecules that exploit our increased understanding of angiotensin receptor structure and function.