Plasma-sprayed HA coating (HAC) 50 and 200 microm thick on Ti6Al4V cylinders was transcortically implanted in the femora of canines. Push-out testing of implant-bone interfaces showed that the HAC coating exhibited higher shear strength at 50 microm coating than 200 microm one. The plasma-sprayed HACs were exhibited compressive residual stresses and the thicker HAC exhibited higher residual stress than that of the thinner HAC. Due to the structure for 50 and 200 microm implants were the same, meaning similar cohesive strength of the lamellar splats. And, there was no difference in the physiological environment; hence the difference of the shear strength for the 50 and 200 microm-HAC implants could best be attributed to the compressive residual stress existed in the HA coating.