Periosteal augmentation of tendons in the course of refixation to bone has been shown to be a suitable method for early primarily stable osteofibroblastic integration. The aim of this study was to evaluate the clinical and radiological results of open rotator cuff reconstruction using an autologous periosteal flap augmentation technique. The research was performed as a prospective cohort study. Twenty-three prospective patients (average age 59.7 years) with degenerative rotator cuff tears were operated on with an open technique and a subtendinous periosteal flap augmentation using bioabsorbable suture anchors and a modified Mason-Allen technique. Clinical evaluation consisted of the Constant-Score and the Simple Shoulder test. Radiological evaluation included standard radiographs and magnetic resonance imaging (MRI). Twenty patients were evaluated at a mean follow-up of 14.4 months. The average Constant Score increased significantly from 51.7 to 80.9 points (p<0.05) with 12 excellent, seven good and one satisfactory result. The Simple Shoulder test showed a significant increase of an average of 4.8-10.7 questions answered with yes (p<0.05). Four patients (20%) demonstrated a retear of the tendon on postoperative MRI. Ectopic ossifications in the supraspinatus tendon were found in four patients (20%) but these had no impact on the final clinical results. Open rotator cuff repair augmented with an autologous periosteal flap shows high patient satisfaction level with low rerupture rates. Mid- and long-term results remain to be seen. The potential benefits compared with conventional open or arthroscopic rotator cuff surgery must be examined in prospective randomized studies.