Biomimetic deposition of hydroxyapatite (HAp) on polystyrene (PS) surfaces under body fluid conditions was evaluated. It was found that introduction of adsorption layers of serum proteins such as human serum albumin (HSA) and human immunoglobulin G (hIgG) on PS surfaces using solution casting techniques resulted in formation of HAp deposits on these surfaces when immersed in 1.5SBF, a solution having 1.5 times higher ion concentrations than those of simulated body fluid (SBF). Experimental results including physical characterizations of the HAp deposits support that the ionic amino acid side chains displayed on the surface of these serum proteins induced heterogeneous nucleation and growth of bone-like HAp. Both HSA and hIgG exhibited HAp deposition ability under the current experimental conditions.