In this work, collagen type I was covalently grafted on the surface of plasma sprayed titania coatings to improve their biocompatibility. The plasma sprayed titania coatings were pretreated by sodium hydroxide to induce the formation of hydroxyl groups which can covalently graft collagen, rendering the collagen having good stability. The dependence of collagen grafting on the sodium hydroxide treatment conditions (concentration, time and temperature) was investigated by measuring the amount of collagen grafted on the titania surface. The biocompatibility of the titania coatings with grafted collagen was evaluated by in vitro cell culture. The results showed that the amount of collagen grafted on the titania coatings increased with the concentration of the sodium hydroxide and the treating temperature, while that on the coating is slightly dependent on the treatment time in sodium hydroxide. In vitro cell culture test proved the positive effects of collagen on the biocompatibility of the plasma sprayed titania coating.