Unicompartmental arthroplasty has proved to be a reliable option for monocompartmental arthritis in well selected patients. Unicompartmental knee arthroplasty (UKA) is not a temporary procedure and its ten year survival is comparable to TKA and better than High Tibial Osteotomy. The success of the procedure depends on strict patient selection, meticulous surgical technique and proper implant selection. The renewed interest in UKA is due to improved results, more conservative nature of the procedure, faster rehabilitation, decreased cost and the minimally invasive techniques. The sedentary patient with unicompartmental arthritis is currently the primary indication for UKA. The role of unicompartmental arthroplasty in younger patients needs more investigation. Revision of UKA has not found to be as complicated as reported in the early series. Minimally invasive UKA has shown short term promising results but more long term studies showing similar implant longevity compared with the standard approach are required to establish its role. Due to high level of patient satisfaction and low morbidity and complications compared with TKA, unicompartmental arthroplasty is an attractive option for patients with predominantly unicompartmental non inflammatory arthritis.