An experimental investigation of the material removal process in abrasive waterjet (AWJ) milling is presented. The experiment was conducted on an amorphous glass for milling channels of controlled depth. It is found that the channels are formed through four different zones, i.e. an opening zone, a steady-cutting zone, a unsteady-cutting zone and a finishing zone. The effect of process parameters on the channel formation process and the major milling performance measures (depth of cut and material removal rate) is then discussed. It is found that AWJ milling is a viable process for machining applications and the milling performance can be reasonably controlled through the selection of process parameters.