A multi-mode compression cell has been developed to study the compression behavior of relatively thin layers of bilogical materials. By a line of reasoning similar to that previously used in advanced soil mechanics, a theory is proposed for the case corresponding to the expression of these materials under constant rate of deformation. In this theory the samples are assumed to be linear materials having a constant coefficient of compressibility, (/ (s)). Providing that fairly thin layers were compressed under relatively slow rate of deformation, this theory was also found to be sufficiently accurate in the case of non-linear materials. The ratio of the measured fluid pressure at the no-flow surface versus the total stress, Pf(I)/P-I seems to be a useful parameter to establish the validity Limits of the proposed theory. The rate of deformation also influences the compression characteristics of the sample, such as the modified coefficient of consolidation. Its impact caries considerably with the sample considered and the Pf(I)/P-I ratio.