PURPOSE: We wanted to evaluate the relationship between the clinical outcomes and cuff integrity after open rotator cuff repair and we wanted to analyze the causes of rotator cuff retear. MATERIALS AND METHODS: 78 patients who underwent open rotator cuff repair were enrolled from 2004 to 2006. All the patients were observed for a minimum follow-up of 12 months and they were evaluated by magnetic resonance imaging (MRI). The clinical outcomes were accessed by dividing the patients into the retear group and the intact group. The groups were also compared to analyze the cause of rotator cuff retear according to the preoperative tear size, the symptom duration, and so on. RESULTS: The clinical outcome of the retear group (n=22) was improved significantly after operation (p<0.001, p<0.001), but the muscle power was not improved significantly (p=0.099, p=0.243). More retears were found in the patients who had a larger preoperative tear (p<0.001) and the symptom duration of the retear group was longer (p=0.027). CONCLUSION: Although there were retear after rotator cuff repair, the clinical outcomes were improved. Yet the muscle power of the supraspinatus and external rotator were not improved significantly. There were more retears for the cases that had a larger preoperative tear size and a longer duration of symptoms.