A theoretical model is developed to describe the affinity-mediated interaction of a suspended cell population and a support surface. The model is capable of describing attachment and detachment phenomena, taking account of both bulk and surface effects. Biospecific interactions between cells and planar surfaces are described using a stochastic Monte Carlo simulation that allows the inclusion of a number of context sensitive rules. The model includes the effects of applied surface shear, ligand and receptor density and binding kinetics. Simulation results are presented which show that the model is capable of providing a qualitative description of experimentally observed responses including attachment rate, Surface rolling and time dependent increases in strength of attachment. The equations derived are numerically tractable and are easily solved using a microcomputer. (C) 2003 Elsevier Ltd. All rights reserved.