We have experienced 3 case of familial hypophosphatemic rickets with proximal renal tubular acidosis. Consisting of a family of 2 years old girl, 7 months old girl baby and their father aged 42 years. Roentgenological studies, biochemical tests on blood and renal function tests revealed hypophosphatemia in all these patients. Metabolic acidosis was found only in the 2 girls. Distal renal tubular acidosis was not found to be responsible for the metabolic disorder according to the sodium bicarbonate (NaHCO3), and ammonium chloride (NH4cl) load testing. No glycosuria, proteinuria and panaminoaciduris were detected, so that Fanconi's syndrome was ruled out and the diagnosis of hypophosphatemia was made.