A 63-year-old woman presented with the clinical picture of classical rheumatoid arthritis. X-ray examination also showed typical aspects of melorheostosis involving both femurs by linear hyperostosis. Humoral and bone scan findings were all in keeping with rheumatoid arthritis. Moreover, a reduced renal phosphate reabsorption and hypophosphatemia were found along with mild hypercalcemia and hypercalciuria. No evident relationships among rheumatoid arthritis, melorheostosis and renal phosphate handling were observed in this case.