tThe leather tanning industry consumes large amounts of water and produces, consequently, significant volumes ofwastewater with high concentration of chemicals and organic matter. One of the main chemicals present in effluentsis the vegetable tannin, which causes a severe environmental impact. With the aim of predicting the performancein chemicals separation of two ultrafiltration (UF) polymeric membranes (OT050 and GR60PP) for potential use in thepurification of the waste stream of vegetable tanning liquors, a synthetic wastewater was prepared. Trials were carriedout at laboratory scale using a flat cell with an effective area of 0.004 m2. The effect of transmembrane pressure inthe permeate flux was studied. Flux decline, fouling resistance and fouling index of the membranes were analyzed.The efficiency of different membranes was assessed using the rejection coefficient for tannins, non-tannins andtotal solids. Analysis of the wastewater treated by UF showed 83% of tannin retention and a recovery of the waterflux after cleaning the membrane GR60PP with water of 41–45%. The rejection coefficient observed for the GR60PPmembrane was higher than for the OT050. There are no previous studies related to the removal of vegetable tanninsin exhausted vegetable tanning bath by using UF polymeric membranes. This study sets a precedent because theresults obtained are very promising regarding permeate flux and rejection observed.