Experimental optimization studies were carried out with the design and operating variables of an elliptical fluid energy mill in order to explore the possibilities of improving its grinding efficiency. It was noticed that the performance of the mill varied with the locations of the nozzles around the outer periphery of the grinding chamber and for a given nozzle size there was a particular spacing between the nozzles giving maximum product fineness. The data collected from the experiments carried out with different heights of the uptake and downtake had indicated that, for a range of grinding nozzle pressures, a circular configuration for the mill with no uptake and downtake yielded better results. The pressure difference across the downtake pipe was monitored using a water manometer while the system was attaining steady state and it was found that the performance of the mill at steady state was very sensitive to the pressure conditions across the downtake pipe. © 1992, Society of Powder Technology Japan. All rights reserved.