We study the multiplicity of positive solutions for a class of fourth-order boundary value problems with non-homogeneous boundary conditions. For this, we use a fixed point theorem of cone expansion/compression type and we establish a general theorem for a type of systems of second-order ordinary differential equations involving parameters. In addition, we apply our result to the study of the existence of solutions for semilinear elliptic systems in bounded annular domains. (c) 2007 Elsevier Ltd. All rights reserved.