In this paper, the mortar finite volume element (MFVE) method with Lagrange multipliers is considered for second order elliptic boundary value problems. We prove L-2 error estimates which are affected by regularities in both the exact solution and the source term. Meanwhile, the uniform convergence of the solution is obtained for the MFVE method under minimal regularity assumption. (c) 2006 Elsevier Inc. All rights reserved.