The change of surface properties by the formation of new surface layers has been successfully carried out by ion assisted reaction (IAR) in which the ion beam is irradiated onto the surfaces with blowing reactive gases near the substrates. Hydrophilic surfaces of polymers (advanced wetting angle of about 10° and surface energy of 60 to 70 mN/m) have been accomplished by the reaction, and the improvements of wettability and surface energy are mainly due to the polar force and hydrophilic functional groups such as C=0, (C=0)-0, C-O, etc., without surface damage. New surfaces of ceramics such as AlON on AlN and AlN on Al203 are formed by the Ar+ irradiation in an O2 environment and in a N2 environment, respectively. Totally wettable thin layers of polymer surfaces on metals have been carried out by optimum plasma zone (OPZ) in which monomer and reactive gases are synthesized in optimum zone of plasma polymerization. Comparisons between the conventional surface treatments and the IAR are described in terms of physical bombardment, surface damage, functional groups, and chain mobility of the polymer. New phenomena of the modified surfaces are reviewed in terms of wettability, surface morphology, surface energy, adhesions to dissimilar materials, adsorption of proteins, etc. Current researches and applications to new material synthesis, to heat exchangers, to electronics, to mass production system, etc. have been discussed with much improved results.