Clinical signs of hypophosphatemia, even when severe, are rare in diabetic ketoacidosis despite their high frequency in this condition. This article presents a patient with rhabdomyolysis due to severe hypophosphatemia, where the level of serum phosphorus was observed to be as low as 0.42 mg/dL on the 16th hour of ketoacidosis treatment. The patient developed acute tubular necrosis due to rhabdomyolysis, but there was no blood reaction in the urine, and the creatine kinase increased to 1200 U/L. The patient was treated without dialysis and was cured after a polyuria period of 2 months after the oliguric period.