With view to develop an amphoteric charged membrane for drug delivery, we have studied the adsorption of insulin on it. In the present study, the amphoteric charged membranes were prepared by pore-surface modification of porous poly(acrylonitrile) (PAN) membranes by grafting with acrylic acid (AAc) and/or N,N-(dimethylamino)propyl acrylamide (DMAPAA). Their surface charge properties and the insulin adsorption behaviors were investigated by zeta potential measurement and UV spectrophotoscopy, respectively, at different pHs. The equilibrium adsorbed amount of insulin correlates well with the charge properties of the membranes and insulin, which indicates that electrostatic interaction played an important role in the insulin adsorption. In addition, adsorption kinetics changed from a Fickian mode to a non-Fickian one when adsorbed amount increased to very high values.