The possibility of obtaining pure water by membrane distillation, from brines rejected in other water production operations has been considered. Membrane distillation experiments have been carried out by using two PTFE porous hydrophobic membranes and sodium chloride aqueous solutions, within a wide range of solute concentrations. The influence of stirring rate, mean temperature and salt concentration on the fluxes has been estimated. The results suggest that a cooperation of membrane distillation and solar distillation techniques may be fruitful.