A satisfactory clinical outcome in cementless total hip arthroplasty depends on the primary stability for rapid osseointegration. While the geometric design of an implant contributes to mechanical stability, the nature of the implant surface itself is also of critical importance. The purpose of this study is to compare implant osseointegration with the following surface modifications made to the titanium alloy Ti6Al4V: machined, grit-blasted, sandblasted and acid etched (SLA), and micro-arc oxidation (MAO). Cylindrical Ti6Al4V implants of the same geometry but with the four different surfaces were tested in vivo in a beagle dog model (femur). The implant - bone shear strength was evaluated by push-out tests undertaken at 24 weeks after insertion into the femur, and the four different Ti6Al4V surfaces were examined histomorphometrically. All the Ti6Al4V implants were well integrated at the time of sacrifice. X-rays revealed that there was no osteoporosis, bone resorption, or osteolysis around the implant. The mean bone-to-implant contact percentages were 22.1±3.8% for the machined group, 52.7±3.7% for the grit-blasted group, 61.3±5.0% for the SLA group, and 64.5±3.2% for the MAO group. The mean bone-to-implant contact percentages were statistically significant between the machined group compared to the grit-blasted, SLA, and MAO groups. The variation in the interfacial shear strength was statistically significant differences between the machined group compared to the SLA, and MAO groups, and the grit-blasted compared to the MAO group. The results of the mechanical testing indicated that the MAO and SLA surface treatments have the potential to enhance peri-implant bone healing.