BACKGROUND: Rotator cuff tears are a common clinical problem, and few long-term studies concerning the outcomes of rotator cuff repairs have been performed. The purpose of this study was to report the fifteen-year outcomes of arthroscopic subacromial decompression with mini-open rotator cuff repair. METHODS: The study included seventy-nine patients who had undergone arthroscopic subacromial decompression with mini-open rotator cuff repair from 1993 to 1996. Outcomes were reviewed in 1997, 2002, and 2010. At the final review, forty-nine patients (forty-nine shoulders) were available or were suitable for evaluation. There were eight large tears, forty medium tears, and one small tear. The patients were assessed with the University of California, Los Angeles (UCLA) score at each evaluation. The mean age of the patients at the time of follow-up was 70.1 years, and the mean follow-up period was 15.6 years. RESULTS: At the time of final follow-up, the outcome was good or excellent in thirty-four patients (69 ), fair in seven, and poor in eight. Three patients required a reoperation. Between the two and fifteen-year evaluations, twenty-nine patients (59 ) had maintained their good or excellent result; the overall raw scores had deteriorated for fifteen patients (31 ), and they had improved for twenty-four (49 ). Forty-one patients (84 ) were satisfied with the final outcome of the shoulder surgery. CONCLUSIONS: This study shows that arthroscopic subacromial decompression with mini-open rotator cuff repair can provide a lasting, durable, and satisfactory outcome for a large proportion of patients fifteen years after surgery. Patient satisfaction at the final evaluation did not necessarily correspond with a good or an excellent UCLA score.