Ball bearings of high-speed dental handpieces were sterilize by various procedures and examined under scanning electron microscopy for evidence of corrosion. The metallic parts of ball bearings (rings and spheres), if not corerctly lubricated, were dramatically corroded in chemical vapor and steam sterilizer. The nonmetallic parts (the retainers made of phenolic resins) appeared to be more sensitive to heat treatments, as revealed by the occurrence of darkening and embrittlement phenomena. In the absence of correct lubrication procedures, the performance of high-speed dental handpieces appears to be adversely influenced by sterilization, mostly in wet envrionments. On the other hand, daily maintenance that follows the manufacturer's instructions reduces and delays the damage to a great extent.