Abstract: An apparatus and method for treatment of medical waste materials, namely a reciprocating autoclave with internal cutters (RAIC), capable of simultaneous crushing and sterilizing of the waste within a waste-treating vessel under a desired temperature and pressure by passing the waste back and forth through the cutters at free falling of the waste materials during the reciprocating of the vessel. It enhances heat penetration onto the small pieces of the fully fractured waste for highly efficient sterilization.