In this study, the diffusion characteristics of Diclofenac-Na through hydrophobic and hydrophilic polyurethane (PU) based membranes are investigated. Hydrophilic polymers are obtained via graft copolymerization of PU with acrylic acid (AA) and crotonic acid (CA). The membranes are prepared by solvent-casting method and characterized by FTIR spectra and SEM analysis. The diffusion measurements are performed using a diffusion cell during 10 h at 37degreesC. Permeability coefficients calculated from diffusion experiments are found to be approximately three times higher in hydrophilic membrane than hydrophobic PU membrane. The adherence of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) onto the membranes at 37degreesC were also investigated. It is determined that the microorganisms didn't adhere onto the membranes compared by control suspension.