Hyperostosis-hyperphosphatemia syndrome (HHS) is a rare autosomal recessive metabolic disorder caused by mutations in the GALNT3 and FGF23 genes. The main features of this disorder include painful swelling of long bones, increased renal reabsorption of phosphate but normal renal function and vitamin D and parathormone levels. Previously, we reported a novel missense mutation in the FGF23 gene in a patient suffering from HHS. In the present report, we demonstrated the same mutation (c.471C>A) in two other cases of HHS with similar clinical manifestations. As this nucleotide change has not been reported previously, it can be a population specific mutation in Iran that can facilitate carrier testing and prenatal diagnosis of HHS.