Fluid is a major component of cartilaginous tissues. Its transport is primarily governed by the hydraulic permeability coefficient of the tissue. The hydraulic permeability coefficient is important to the understanding of the transport processes of interstitial water and ions [e.g., Gu et al, 1993] and the viscoelastic behavior of the tissue [e.g., Mow et al, 1980; Setton et al, 1993]. However, the hydraulic permeability coefficients of these tissues are extremely low and difficult to quantify precisely. Studies in the literature report on the determination of the hydraulic permeability of these tissues directly by measuring fluid flux corresponding to the applied pressure difference in a permeation experiment [Edwards, 1967; Mansour and Mow, 1976; Mansour and Matsumoto, 1998; Maroudas and Bullough, 1968; McCutchen, 1962] or indirectly by curvefitting experimental data from confined compression or indentation tests using the biphasic theory[e.g., Athanasiou et al, 1991; Best et al, 1994; Drost et al, 1995; Houben et al, 1997, Iatridis et al, 1997; Mak et al, 1987; Mansour and Matsumoto, 1998; Mow et al, 1980; Setton et al, 1993]. Recently, Gu and co-workers (1998) reported that the permeability coefficient of human anulus fibrosus determined directly was one order of magnitude greater than that determined indirectly [e.g. Best et al, 1994, Drost et al, 1995, Houben et al, 1997, Iatridis et al, 1997]. To address this discrepancy, we investigated the hydraulic permeability coefficients of human lumbar anulus fibrosus and bovine articular cartilage using a new technique developed by Gu and co-workers (1998). The hydraulic permeability coefficient of human anulus fibrosus was compared to that of bovine articular cartilage measured under the same testing conditions.