Performing energy and mass transformation within microstructured reactor or processes at industrial scale requires the arrangement of a large number of microchannels (numbering-up process). Appropriate design for uniform flow distribution is a key feature to ensure optimal performance of these channel networks. The present study performs a hydrodynamic analysis of these multi-scale networks under isothermal and laminar flow conditions. The main objective here is to rapidly select an appropriate numbering-up operation, without requiring a large computational power. Therefore, several network configurations are analyzed and compared on the basis of hydrodynamic criteria of interest, such as the flow distribution and the required pumping power. Under a set of geometrical constraints, an optimal multi-scale network can be derived. (c) 2008 Elsevier B.V. All rights reserved.