Seawater desalination by reverse osmosis (RO) is widely used for drinking water production. In order to reduce the volume of brines and to increase recovery, a new approach is proposed in the frame of the European MEDINA project. It lies on a combination of RO and Vacuum Membrane Distillation (VMD) in order to over concentrated RO retentates and to reduce their volume. Indeed, VMD can be used for concentrated salty solutions, because concentration polarization and temperature polarization might be non limiting even for quite high salt concentrations. The objective of this paper is to provide some first trends on the feasibility of using VMD for enhancing the global process recovery. The approach is firstly based on simulations for highly concentrated solutions using a VMD modeling based on Knudsen diffusion through the membrane which was improved to take into account highly concentrated waters. The model was validated by experimental results obtained with different salty solutions and with both flat-sheet...