In vivo adsorption of salivary albumin and alpha-amylase onto titanium, enamel and dentin was analysed following their exposure to the oral cavity for 2h. Oral appliances in six adults served as a platform for carrying 4-mm discs of the three materials. Adherent proteins were eluted from the discs and the amounts of salivary albumin and alpha-amylase were measured by an enzyme-linked immunosorbent assay. While significant difference between the adsorption of albumin and alpha-amylase onto enamel as compared with dentin was observed, adsorption onto titanium was significantly lower. A sample of whole saliva was also collected from each participant. The mean total amounts of albumin and alpha-amylase in the participants' whole saliva were 0.03 and 0.54 mg ml-1, respectively. Titanium adsorbed significantly less (4.43%) of the total albumin than did enamel (14.30%) or dentin (18.80%). No significant difference was found in the relative amounts of alpha-amylase adsorbed by the three materials. This significantly selective adsorption of proteins may enable the attachment of specific bacteria and thus alter the composition of the dental plaque and its potential pathogenicity.