Abstract Plasma wall interactions have been recognized as an important topic since early tokamak machines. Reactor calculations and the search for scaling laws recently gave a new impetus to this subject. Better control of both the light and heavy impurities is now obtained. In the last two years the effective ionic charge has been reduced to almost one in present machines. Details are given comparing the results from different laboratories. Pre-cleaning and gettering of the walls as well as lowering the temperature of the edge plasma have proved to be efficient. Comments are made on future developments.