One hundred four patients undergoing THA were randomized to receive either cementless large-head metal-on-metal (MoM) THA (n=50) or cementless metal-on-polyethylene (MoP) THA (n=54). The primary outcome of interest was survivorship free from revision for any cause at 10 years. Secondary outcomes included pseudotumor formation, functional outcomes (Oxford Hip Score and Harris Hip Score), and serum cobalt and chromium ion levels. At 10 years, 81 patients (78% of the original cohort) completed follow-up, with 36 in the MoM group and 45 in the MoP group. Overall, the results showed no significant difference in survivorship free from revision between groups. However, pseudotumors were significantly more frequent in the MoM group , and elevated cobalt and chrome levels were exclusive to MoM patients. Functional outcomes did not differ between groups. These findings suggest that while large-head MoM THA has comparable long-term survivorship to MoP THA, the increased risk of pseudotumors and elevated metal ion levels warrants continued surveillance.