The unicompartmental knee arthroplasty is an interesting and potentially beneficial procedure that remains a controversial alternative to total knee arthroplasty and high tibial osteotomy. A critical review of the literature reveals inconsistent results using this compartmental approach to joint resurfacing. Many of the inconsistencies, however, are attributable to improper patient selection, poor component position, or inaccurate component alignment, leading to further degenerative changes and subsequent return of pain. The more recent studies, however, suggest better and more consistent results. The current indications for unicompartmental arthroplasty along with the ideal prosthetic qualifications are presented. To justify including this procedure as a sound alternative in the treatment of unicompartmental arthritis of the knee joint, however, further clinical studies are warranted.