This retrospective study compares the short-term outcomes of small-incision unicompartmental knee arthroplasty (41 patients) with standard total knee arthroplasty (TKA) (50 patients) in 91 consecutive patients older than 70 years. Knee Society Scores and range of motion (ROM) were assessed preoperatively, at 6 weeks and 6 months, and through a minimum of 2 years. Postoperative comparisons included blood loss, transfusions, narcotic consumption, length of hospital stay, and complications. While Knee Scores and ROM were similar preoperatively, both were better in the unicompartmental group at each postoperative time interval. Patients with unicompartmental replacements had a much quicker return of function and discontinuation of pain medication. Blood loss was significantly more for the TKA group, as was the need for blood transfusion. None of the unicompartmental patients required transfusion. Narcotic use and length of hospital stay were also significantly less for the unicompartmental group. The overall rate of postoperative medical and surgical complications was similar for the 2 groups, with 1 major complication in each. Overall, the physiologic impact of unicompartmental knee arthroplasty was much less than TKA in this older patient population and resulted in a faster recovery.