Tendon augmentation grafts have the potential to facilitate the repair of massive or otherwise unrepairable rotator cuff tears. In our clinic, between 2009 and 2013, 25 patients underwent surgery to treat massive symptomatic rotator cuff tears with porcine dermal collagen patch. This study is a clinical and instrumental assessment of 9 patients with the longest follow-up. These patients were evaluated with Constant score, the American Shoulder and Elbow Surgeons Evaluation Form, ultrasound imaging, magnetic resonance imaging, and electromyography. The clinical evaluations have shown good outcomes. The magnetic resonance imaging results were comparable with those of the ultrasound scan. In all cases, we found covering of humeral head, centering of the humeral head, maintenance of the tropism of the supraspinatus, no appearance of fatty degeneration, no worse in cases with fatty degeneration. With the electromyographic examination a complete functional recovery was observed with the possibility of performing maximal contraction against resistance in all cases. We believe that porcine dermal collagen is effective as an augmentation graft in the treatment of chronic extensive rotator cuff tears, providing excellent pain relief with an improvement in active ranges of motion and strength.