BACKGROUND In the case of rotator cuff tears, the severity of the muscle atrophy and fatty degeneration has an effect on the success of the repair and on the functional outcome after surgery. OBJECTIVE The ability of regeneration reduces with ageing; therefore, the study examined the atrophy and the fatty degeneration after rotator cuff repair in patients over 65. METHODS Eleven patients over 65 years of age were involved whose surgery was performed at the Department of Orthopaedics of Semmelweis University between 2012 and 2015. Their average age was 71.9 years and the average follow-up period was 39.9 months. Tear sizes were C1 in 3 cases, C2 in 3 cases, C3 in 4 cases, and C4 in 1 case. Each patient had magnetic resonance examination before and after the repair; the muscle atrophy and fatty degeneration were evaluated together with the type of the tear. Visual analogue scale and Constant score were used for the assessment of the pain and the shoulder function. RESULTS The average Constant score was 75 points. The occupancy ratio - referring to the severity of the atrophy - did not show significant improvement. The change in fatty degeneration and the atrophy were examined in different groups according to the size of the tears. In each group, the results showed progression. CONCLUSIONS After rotator cuff repair in patients over 65, fatty degeneration and muscle atrophy also show progression. No significant relationship was found between the size of the tear and fatty degeneration or between the size of the tear and muscle atrophy. Orv Hetil. 2019; 160(14): 533-539.