The Centre For Engineering Research Inc., now C-FER Technolgoies Inc. (C-FER), New Paradigm Engineering Ltd., and a consortium of over 39 oil producers and equipment suppliers have spent the last six years developing and testing a Downhole Oil/Water Separation (DHOWS) process which consists of hydrocyclones and conventional pumping equipment. By end 1996, over 18 field trials were completed using electrical submersible pumps (ESP), progressing cavity pumps (PCP) and beam pumping systems in a wide variety of conditions. In the original prototype ESP application, water reductions of up to 97% were achieved. Generally, the water oil ratio (WOR) to surface can be reduced to two or less. A brief summary is provided of the field trials completed and the key results achieved, including oil production increases, water reduction, predicted increases in reserves recovery and general factors affecting a successful DHOWS application. The challenges which have been overcome are discussed together with an outline of potential future applications and challenges. It is anticipated that DHOWS applications will soon change the current paradigms of the industry in relation to what is possible in the area of water management.