Brownian dynamics simulation has been employed to study the diffusion behavior Of nutrient molecules in a random Porous scaffold, which models a realistic one made by a gas-foaming technique. Excluded Volume interaction between nutrient and the pore wall is only considered and implemented with reflecting boundary condition. Several effects are investigated, including the medium porosity, the scaffold microstructure and the size ratio of nutrient to pore. It is found that unlike in ordered porous media, the effective nutrient diffusivity in random media depends not only on the porosity, but also on degree of pore interconnection and overlapping, which is affected by the pore number concentration. At a given porosity, the diffusivity may increase noticeably when the pore number concentration becomes high enough. This behavior arises when the porosity is not too large (lower than 80%). (C) 2009 Elsevier Inc. All rights reserved.