Legionella pneumophila is a cause of community-acquired pneumonia that is reported to induce electrolyte disorders, including hyponatremia, hypokalemia, and hypophosphatemia. We herein report two Japanese men with Legionella pneumonia and hyponatremia and hypophosphatemia. These findings were associated with an elevation of urinary low-molecular-weight tubular protein, including urinary β2-microglobulin, N-acetyl-β-D-glucosaminidase, the fractional excretion of phosphate and uric acid, and the presence of glycosuria and panaminoaciduria, suggesting that their electrolyte disorders had been caused by Fanconi syndrome. In these two cases, hyponatremia was probably due to salt wasting. Electrolyte disorders caused by Legionella pneumonia are corrected by treatment of the primary disease and fluid administration.