A case of glenohumeral osteoarthritis in a 35-year-old female following a color test during rotator cuff repair is described. The patients had a tear in the rotator cuff involving the supraspinatus muscle and rotator interval. A color test with a 0.4% aqueous solution of gentian violet was performed during the operation and the ruptured cuff was not tightly sutured. The patient developed glenohumeral osteoarthritis 25 months postoperatively. Plain film radiographs showed joint space narrowing and bone sclerosis of the humeral head, but there was no evidence of osteophytes. This pathology was thought to have been caused by the aqueous gentian violet solution.