In industry, resin flow prediction is a real challenge, because filling defects, such as dry spots and porosities, can dramatically degrade the mechanical properties of the shaped part. The present contribution investigates the use of the boundary element method for the numerical simulation of resin flow in liquid composite molding processes. Due to the dual‐scale structure of the reinforcement, there are two different approaches in the literature to simulate the flow: the macroscale, well suited for the mold design, and the microscale, usually used for the local analysis of the reinforcement impregnation. In this work, both scales are under consideration. The article presents the numerical methods used to solve Darcy's law and Stokes equations with boundary integral formulations. Typical applications are given to illustrate both methods, and numerical validations are performed using comparisons with experimental and analytical data. The results show that the methods provide a high accuracy and a low CPU time. POLYM. COMPOS. 34:1235–1244, 2013. © 2013 Society of Plastics Engineers