This work addresses the removal of glucocorticosteroids (hydrocortisone, HYDRO; and dexamethasone, DEXA) and anesthetics (procaine, PROCA; and lidocaine, LIDO), from water with commercially available reverse osmosis/nanofiltration (RO/NF) membranes. The RO/NF experiments were of long-run type (24 h) in order to accomplish steady-state and to obtain accurate rejection of the selected compounds. The removal of the examined compounds with the RO (XLE, SWC1, LFC–1) and the tight NF (NF90) membranes was higher than 98 %. Relating the solute rejections to membranes\u27 properties has shown that the dominant rejection mechanism of the examined pharmaceuticals by all the membranes was the size exclusion effect. Rejection factors for hydrophilic HYDRO and DEXA compounds confirm that they do not adsorb onto the active layer of the selected membranes. LIDO and PROCA, slightly hydrophobic compounds, had lower rejections after 24 h treatment compared to
initial values, and probable they were adsorbed onto polymeric matrix of active layers
