First wall, divertors, and other components of the vacuum chamber of a fusion reactor will be submitted to ion bombardment from the thermonuclear plasma. The effects of this bombardment on the materials must be known in order to foresee and correct any major problem. Particular attention must be given to the erosion of the materials. The major mechanisms responsible for wall erosion in a fusion device, namely sputtering, blistering, and evaporation, are revised. The erosion rate due to sputtering is reported for different materials and bombarding energies. A review of the effects of blistering on surface morphology and erosion is made as a function of energy, ion dose, and temperature of the material. The evolution of surface temperature under various bombardment power is given and correlated to probable evaporation rates. The relative importance of these different phenomena is assessed.