Tannery industries generate wastewater containing high sulphate concentrations as sulphates are salts widely used in the tanneries as auxiliary matter. Some residual floats from tanneries (pickling, chrome tanning and dyeing) contribute to the final sulphate discharge. In order to predict NF membrane behaviour after filtering different tannery floats, a simulated wastewater was made. The effect of conductivity on the permeate flux and on chloride and sulphate retention was studied. Experiments were carried out in a laboratory plant equipped with a spiral-wound module of 2.51 m(2) of active surface. Chloride retention lower than 20% was measured, and the membrane permeate fluxes were around 18 L center dot m(-2)center dot h(-1) for feed conductivities higher than 85 mS/cm.