Diuretics have been the cornerstone of acute heart failure (AHF) therapy for >200 years, although the treatment of chronic heart failure has changed dramatically over the past decades with the introduction of angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists, beta-blockers, and aldosterone inhibitors. These treatment modalities were never tested prospectively in the acute setting. Furthermore, there is a significant lack of prospective data on the use of diuretics in both chronic (CHF) and AHF. Hence, despite lack of knowledge on their efficacy and safety, diuretics remain an essential component of the current management of AHF and CHF. In the present manuscript we will address the practical concerns regarding diuretic selection, dosage, combination regimens, and the importance of achieving clinical improvement with minimal changes to kidney function in patients with AHF. Heart Fail Monit 2008;6(1):9-19.