Abstract: Alzheimer`s amyloid βA4 protein fused with glutathione S-transferase (GST) was highly expressed using a strong prokaryotic expression system in Escherichia coli. The expressed protein had expected molecular mass on SDS-PAGE and appeared exclusively immunoreactive with antibody specific for βA4 epitope. This recombinant protein was purified with a combination of urea solubilization and ion exchange chromatography. To identify the human serum proteins which interact with βA4, affinity columns were prepared by immobilizing GST- βA4 and GST respectively. Using the affinity columns and human serum, we have observed an interaction of βA4 with serum proteins. Two proteins of Mr 45 and 15 kDa were identified on SDS-PAGE to be involved in the interaction. Our demonstration of the ability of βA4 to interact with serum protein strongly support the notion that such an interaction may underlie with the biological function of βA4 in vivo.