Sixty-six patients with primary or secondary osteoarthritis undergoing total hip arthroplasty were randomized intraoperatively to receive either a cementless press-fit solid-backed tantalum acetabular component without ancillary screw fixation (n=33) or a cementless press-fit titanium fiber-metal acetabular component with one ancillary screw (n=33). The primary outcome was proximal acetabular component migration measured by radiostereometric analysis (RSA). Secondary outcomes included migration across other axes, rotation, and Harris Hip Scores. Migration was assessed at baseline (4–6 days), 6 weeks, 3 months, 1, 2, 3, 5, and 7 years. Overall, the results of the study revealed that the mean proximal migration of tantalum components was non-inferior to that of titanium components at both 5 and 7 years. These findings suggest that tantalum acetabular components without ancillary screws offer comparable mid-term stability to titanium components with screws in primary THA.