Sterilization by gamma radiation is the latest and perhaps the most available methods. However, the effect of gamma radiation on structure and physical properties of dental materials that have been recently developed and introduced to the dentalmarket were not investigated. The aimof our research was to investigate the effect of high energy gamma radiation on microstructure, surface hardness and surface roughness of dental porcelain. Matrix microstructure of dental porcelain changed after exposure to gamma radiation doses. Surface hardness of dental porcelain decreased but surface roughness increased after exposure to gamma radiation doses. Surface dental porcelain color (white) changed into dark color.