This paper presents the results of an experimental study on the effect of recycled aggregates on concrete subjectedto high temperatures. Concretes with natural aggregates (0S-0G), 30 % substitution of recycled concretecoarse aggregates and sand (30S-30G), and 100 % substitution of recycled gravel (0S-100G) were studied. Theinfluence of recycled aggregates on the evolution of the thermophysical properties of concrete as a function oftemperature when heated to 600 ◦C and then cooled, as well as on the temperature distribution within a cylindricalspecimen was investigated. Thermal deformation measurements from 20 ◦C to 800 ◦C showed thefavourable influence of the substitution of siliceous sand by recycled sand. For all concretes, residualscompressive strength and elastic modulus decrease and porosity increases with the temperature.