A mathematical model is developed for indentation tests of articular cartilage. The cartilage, normally bonded to the subchondral bone, is modeled as an infinite elastic layer bonded to a rigid half space, and the indenter is assumed to be a rigid axisymmetric punch. The problem is formulated as a mixed boundary value problem of the theory of elasticity and solutions are obtained for the indentation of the layer by the plane end of a rigid circular cylinder and by a rigid sphere. Subject to detailed verification with independent tests, the present solutions are suggested as useful for the determination of the elastic shear modulus of intact cartilage.