Purpose: To evaluate of the clinical usefulness of minimal invasive ulnohumeral arthroplasty in patients with mild to moderate elbow arthritis. Materials and Methods: From January 2000 to December 2008, twenty-nine patients with mild to moderate elbow arthritis underwent minimal invasive ulnohumeral arthroplasty. Among these patients, we reviewed the cases of 24 patients for whom we had follow-up data for at least 1 year. There were 20 males and 4 females with a mean age of 53 years (range: 31~69). We excluded patients with preoperative ulnar neuropathy symptoms and investigated the mean operation time, the joint range of motion, the time required until the start of joint exercise, and the Mayo elbow performance score (MEPS). Results: Passive and active joint exercises were started in an average of 1.8 days (range: 1~4) after surgery; the mean operation time was 38 minutes (range: 25~55). The elbow joint range of motion was 25-104 degrees (extension 0~70, flexion 80~130) preoperatively and was improved 40 degrees on average to 14-133 degrees (extension 0~45, flexion 90~150) after a year of follow up. The average time required until the start of joint exercise was 1.6 days (range: 1~5). MEPS were excellent in 9 cases and good in 5 cases after a year of follow up. Although there was 1 case of delayed wound healing and 7 cases of postoperative edema, they improved spontaneously. Conclusion: For patients with mild to moderate elbow arthritis, minimal invasive ulnohumeral arthroplasty is a clinically useful surgery since its operation time is short, early joint exercise is possible, and pain is mild.