Current investigation into the effect of fire on building components are usually carried out on full scale structural elements subjected to very high temperatures to simulate the conditions in a real fire. the structural elements tested in this manner are either steel or concrete members without any protective coatings. However, structural elements in actual buildings are usually plastered with cement-sand mortars or gypsum based plasters before painting. This investigation was aimed at studying the effect of plastering on the residual compressive strength of standard concrete cubes after fire.