For protein chip construction, the chemical properties for the surface of glass slides have to be elaborately modified for protein immobilization. To immobilize proteins, plasma polymerized hexamethyldisiloxane (PPHMDSO) thin film was deposited onto the surface of glass slide. Previously, it was reported that proteins were immobilized onto PPHMDSO thin film [H. Miyachi, A. Hiratsuka, K. Ikebukuro, K. Yano, H. MLIgUrUma, I. Karube, Biotechnol. Bioeng. 69 (3) (2000) 323-329]. Flere, we modified PPHMDSO-coated glass slide by an additional oxygen plasma treatment with placing the patterned mask on the HMDSO-coated glass slide. Hydrophilic Surfaces were detected by measuring the contact angle of water. Of great interest, proteins were strictly immobilized on the patterned 02 plasma treated areas, providing more efficient ways for fabricating the protein chips. (c) 2005 Elsevier B.V. All rights reserved.