To prepare silica beads covered with a lysozyme-imprinted polymer layer, we polymerized acrylamide and acrylic acid or acrylamide and N,N-dimethylaminopropylacrylamide with (NH4)(2)S2O8 in a phosphate buffer containing the lysozyme, surface-modified silica beads, and crosslinkers; the result was the formation of a polymer layer with a lysozyme recognition site on the silica-bead surface. By quantitative analysis of the supernatant of the solution containing the silica beads, we confirmed that modified silica beads, in contrast to unmodified silica beads, can selectively adsorb lysozymes. The process of binding and releasing the lysozyme to and from the modified silica beads can be repeated several times without degradation of the rebinding ability. A quartz-crystal microbalance sensor fabricated with a molecularly imprinted polymer layer with a lysozyme recognition site was prepared. When a lysozyme aqueous solution was added to the solution in which the sensor was immersed, a high level of sensitivity and response was observed. High selectivity was also demonstrated by tests with other protein solutions.