Background and Purpose Hemipelvectomy is a life-changing treatment for pelvic malignancies. This study compared functional outcomes and quality of life of patients following internal or external hemipelvectomies. Subjects Ninety-seven patients who underwent tumor-related internal (n=39) or external (n=58) hemipelvectomy surgery between January 1, 1988, and December 31, 2004, participated in the study. Methods Using a descriptive retrospective cohort study design, functional status was evaluated with the Barthel Index at 3 time points. Quality-of-life parameters were evaluated at follow-up using the Linear Analog Self-Assessment tool (LASA). Results Data were collected on all 97 patients at rehabilitation consultation and hospital discharge. Follow-up data were obtained via survey on 44% of the original group at a median of 5.8 years (interquartile range [IRQ]=1.7–10.4) after surgery. Median total Barthel Index scores were similar between the internal and external hemipelvectomy groups at the initial physical medicine and rehabilitation assessment (10 [IQR=10–15] versus 10 [IQR=3.75–15]), at discharge (40 [IQR=30–65] versus 50 [IQR=35–66.25]), and at follow-up (92.5 [IQR=76.25–100] versus 92.5 [IQR=78.75–96.25]). Participants with external hemipelvectomies were less independent in bladder function and experienced greater pain severity at follow-up compared with those with internal hemipelvectomies. Overall quality-of-life parameters were similar between the groups. Discussion and Conclusion Despite significant differences in surgical procedures, immediate and long-term functional outcomes and quality-of-life parameters were similar among participants with internal and external hemipelvectomies.