Seven series of tests have been performed on specimens from five natural soft clay sites to determine the variation of the vertical and horizontal permeabilities when the soil is unidimensionally compressed. The results show that the permeability anisotropy does not increase significantly with compression up to strains of 25% for marine clays. In varved clays, mostly because the clay laminae are more compressible than the silty laminae, the anisotropy increases with vertical compression. Key words: permeability, clay, anisotropy, laboratory, compression.