<p>This paper presents a laboratory investigation of inherent anisotropic stiffness of natural Bangkok Clay under an isotropic stress condition over small- and intermediate-strain ranges. A triaxial apparatus, equipped with local strain measuring systems and bender element system, is employed. During isotropic consolidation, observations are made on small-strain shear modulus (<i>G</i>_<i>vh</i> and <i>G</i>_<i>hh</i>) and intermediate-strain deformations (<i>ε</i>_<i>v</i> and <i>ε</i>_<i>h</i>), and the data are analyzed in terms of shear, bulk, and coupling moduli and their degradation. The results reveal that very soft to soft Bangkok Clay is relatively isotropic; however, medium Bangkok Clay shows more anisotropic characteristic at both small and intermediate strains. The anisotropic characteristics of medium Bangkok Clay are presented by having <i>ε</i>_<i>v</i>/<i>ε</i>_<i>h</i> = 1.5 and <i>G</i>_<i>hh</i>/<i>G</i>_<i>vh</i> = 1.18 during isotropic consolidation. Empirical equations to predict anisotropic in-situ small-strain shear moduli of Bangkok Clay are proposed. Alternative simplified empirical equations, as a function of water content, are also presented for practical use. The bulk and coupling moduli of Bangkok Clay are analyzed. The small-strain bulk and coupling moduli of very soft to soft clay are approximately constant with depth, whereas those of medium clay may be predicted from the initial void ratio. The ratio of small-strain coupling and bulk modulus (<i>J</i>/<i>K</i>) is approximately 6. In general, very soft to medium Bangkok Clay has a low degree of inherent stiffness anisotropy compared with that of other clays reported in the literature.</p>