Chemical composition and microstructure of individual phases of corroded high zirconia fused cast (HZFC) refractory have been examined in various places and distances from the interface with molten glass of different compositions. An unused HZFC block (ER 1195RT) as well as blocks corroded by lead glass for lighting purpose, container white glass and Simax glass, respectively, have been investigated. Static crucible corrosion tests have been carried out at 1450 deg C for 100h. Samples of refractories were studied by means of scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction. The greatest changes were observed only in the glassy phase composition of individual corroded samples.