Hypophosphatemia is an electrolyte disorder frequently faced in inpatient and outpatient practice. Associated symptoms are very variable but are often nonspecific. The consequence is that it might be overlooked. Yet, when severe, hypophosphatemia is associated with a significant morbi-mortality and, therefore, needs to be identified and treated appropriately. Treatment goes from identifying the cause to substitution according to whether it is symptomatic or not and its severity. Mild to moderate hypophosphatemia needs substitution only when symptomatic which will be administrated orally, while severe hypophosphatemia requires an intravenous substitution. We review here situations at risk of hypophosphatemia, its clinical manifestations and its management in terms of diagnostic and treatment.