The influence of calcium (Ca) at titanium surface on co-precipitation of Ca-P and bovine serum albumin (BSA) has been investigated by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The titanium surface containing Ca was prepared by immersing titanium plates into a saturated calcium hydroxyl (Ca(OH)(2)) solution. A solution containing BSA, calcium and phosphate ions was used for the co-precipitation test. Both BSA and calcium phosphate co-precipitated onto titanium surfaces with and without Ca. For the former, however, a thicker carbonate apatite coating, which consisted of finer crystal grains, formed and more protein precipitated compared to the surface without Ca. These results indicated that Ca at the titanium surface was favorable to the co-precipitation of BSA and Ca-P. Moreover, chemical interactions probably occurred during the co-precipitation of BSA and Ca-P.