The intrinsic permeability k of preforms of packed alpha-SiC particles having monomodal and bimodal particle size distributions has been evaluated by pressureless infiltration of a wetting organic fluid at room temperature. The study was carried out using SiC particles of average diameters in the range 4.88-168 mu m and bimodal mixtures of particles with diameters of 16.9 and 168 mu m. The experimental results for monomodal preforms can be fitted by Hazen's law, k alpha D(10)(m), D(10) being the particle size for which 10% of particles are finer, with an exponent m = 1.76 not far from that proposed by Hazen (m = 2). Data for bimodal mixtures cannot be, however, described by Hazen's law due to the large changes in volume fraction that are promoted by varying the relative amount of the two particles. Instead, data for both monomodal and bimodal preforms can be satisfactorily fitted by Kozeny-Carman equation that incorporates particle volume fraction as one of the parameters.