154 patients scheduled for total hip replacement were randomized to undergo either conventional manual implantation of an S-ROM prosthesis or robotic-assisted implantation of such prosthesis using the five-axis ROBODOC. Patients were assessed clinically and radiographically through a 24 month follow-up period. Eighteen percent (18%) of attempted robotic implantations failed and had to be converted to manual implantation. Limb-length equality and varus-valgus orientation of the stem were better immediately postoperatively in the robotic group. By 24 months, no significant differences were found between the groups in terms of clinical scores. Dislocations were significantly more frequent in the robotic surgery group (11/61 compared to 3/80), as were revision surgeries (8/61 compared to 0).