Alumina membrane filters in the form of thin (0.3-0.8 mm) discs of 25-30 mm diameter suitable for microfiltration application, have been fabricated by the tape-casting technique. Their pore size could be varied in the range 0.1-0.7 mu m and porosity in the range 25%-55% through optimization of experimental parameters. The most important factor which determines the pore size, is the initial particle size of ceramic powders used for this purpose. Temperature of firing, and also the soaking time are crucial parameters which determine the porosity. Water permeability under suction conditions varies in the range 110-900 lm(-2)h(-1) depending on porosity, pore size and thickness of the membrane. Most of these membranes, particularly those with pore sizes less than 0.5 mu m, are found to be suitable for complete removal of bacteria from water and are also reusable after cleaning by acid or heat sterilization.