An elevation of arterial blood pH called alkalosis remains an underestimated condition in hospitalized patients. Serious alkalosis can be associated with high risk of death. The disorder can be caused by increased concentration of bicarbonate (metabolic alkalosis) or decreased concentration of carbon dioxide (respiratory alkalosis). In most cases of metabolic alkalosis it is generated by vomiting or diuretic use, whereas respiratory alkalosis is provoked by hyperventilation associated with respiratory or neurological disorder. Maintenance of metabolic alkalosis is possible only in patients with impaired renal base excretion which is most often produced by hypochloremia. In both respiratory and metabolic alkaloses treatment depends on the underlying factor. In hyperventilation syndrome is based on behavioral therapy. In most cases of metabolic alkalosis the administration of sodium and potassium chloride forms a substantial part of therapy.