A nanowire-filled membrane of porous anodic alumina is resolved by noncontact electric force microscopy. On nearly completely filled matrix areas, hillocks of about 50 nm diameter are observed. From the imaging of the tip-sample capacitance they could be identified as the endings of protruding Ag wires. Some are covered with matrix residues of about 10 nm diameter which could be resolved in the capacitance image. Sample parts with smaller filling amounts show that phosphoric acid enlarges the pore diameters. We conclude that the wire diameters appear to be smaller than the inner pore diameters.