Reinforced electrocast zirconia refractories

A reinforced electrocast zirconia refractory obtained by heating fully stabilized electrocast zirconia refractories containing 89.0 to 97.5% by weight of ZrO.sub.2, less than 1% by weight of SiO.sub.2, less than 1% by weight of Al.sub.2 O.sub.3 and 2.5 to 8.0% by weight of a stabilizing agent to a temperature of at least about 1400.degree. C. in an atmosphere containing from 1.5 to 30% volume of oxygen, a raising rate of temperature being less than 85.degree. C./hour during the period from the time when temperature reaches about 600.degree. C. to the time when the temperature reaches about 1400.degree. C., and maintaining said stabilized electrocast zirconia refractory at the temperature of at least about 1400.degree. C. at least for 30 minutes.