Hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HA) is materials mainly known for its special ability to contact bone tissue. In this study, bone like apatite formation was investigated at the titanium (Ti) surface with functional groups, -COOH, -NH2, and -OH respectively. Ti surface was modified by depositing a thin polymeric film containing COOH, NH2, and OH groups through plasma polymerization of acrylic acid, ally amine and allyl alcohol. Plasma polymerization carried out at a discharge power of 50 W for 5 min. Modified Ti samples were evaluated by immersed in simulated body fluid at 36.5 degrees C for 4 days and 7 days. COOH/Ti was favorable for bone-like apatite formation when compared with untreated Ti, NH2/Ti and OH/Ti. (C) 2012 Elsevier B.V. All rights reserved.