Hypoaldosteronism is a clinical condition characterized by a deficiency of aldosterone or its impaired action at the tissue level. The disorder may result from disturbances in renal renin production and secretion, conversion of angiotensin I to angiotensin II, adrenal aldosterone synthesis and secretion, or from abnormal responsiveness of the target tissues to aldosterone. Hypoaldosteronism has a wide spectrum of clinical manifestations, ranging from asymptomatic hyperkalemia to life-threatening depletion of fluid volumes. Although the disease, if unrecognized and untreated, seems to be associated with increased morbidity and mortality compared to the normal population, it was surprisingly rarely reviewed in the literature. The aim of this paper is to summarize the present state of knowledge on the etiology, clinical presentation, diagnosis and treatment of various forms of hypoaldosteronism.