One thousand five hundred eighteen patients (1716 hips) with end-stage hip disease were randomized to receive either an ultra-short cementless anatomic femoral stem (n=759, 858 hips) or a conventional length cementless anatomic femoral stem (n=759, 858 hips). The primary outcome of interest was the long-term clinical and radiographic outcomes, including the Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and University of California Los Angeles (UCLA) activity scores. Secondary outcomes included patient satisfaction, incidence of thigh pain, stress shielding, and implant survival rates. Outcomes were assessed over a mean follow-up period of 16.5 years in the ultra-short stem group and 17.5 years in the conventional stem group. Overall, the results revealed no significant differences in clinical scores, patient satisfaction, or implant survival rates. However, the ultra-short stem group experienced significantly lower rates of thigh pain (0.7% vs. 15%, P=0.001) and stress shielding (P=0.001) compared to the conventional length stem group. These findings suggest that ultra-short cementless femoral stems provide equivalent long-term outcomes while reducing complications related to stress shielding and thigh pain.