The zirconium--dysprosium system was investigated by melting point, thermal analysis, resistivity, x-ray, and metallographic methods. Results indicate a single eutectic system with a peritectoid reaction occurring at 890 deg C. The eutectoid isotherm extends from 30 to 95% dysprosium at 1280 deg C. Solid solubility of dysprosium in alpha and beta zirconium is extensive. No definite values are given for the extent or solid solubility of zirconium in dysprosium. (J.R.D.)