The removal efficiency and rejection mechanisms of three pharmaceutical molecules, ibuprofen, diclofenac and metoprolol, using commercial ultrafiltration, nanofiltration and reverse osmosis membranes with different surface characteristics, were reported. The adsorption behaviours of pharmaceutical molecules on each membrane surface were studied and found to be related to the surface charge of membranes. The influence of individual and a mixture of pharmaceuticals on the rejection behaviours of membranes was evaluated. The nanofiltration membranes showed near-complete removal of all pharmaceuticals in mixture solution. On the other hand, retention capabilities for the membrane with individual pharmaceutical solutions varied and were influenced by the characteristics of the pharmaceuticals. A mixture of pharmaceuticals forms different types of fouling on the membrane surface that influence the rejection rates.