The aim of this study was to determine whether lymphedema of the arm is associated with traumatic injury to the shoulder and to assess the role of lymphatic physiotherapy in reducing disabling shoulder pain. The study group consisted of 10 women aged 58-81 years (mean 66.9) with arm lymphedema after surgery for breast cancer. The average interval between the operation and the appearance of lymphedema was 9.8 years. All patients complained of shoulder pain. Five patients had a tear in the supraspinatus muscle diagnosed by ultrasound examination, and 5 had chronic bursitis; the nonaffected arm showed no pathology. The mean volume of the affected arm was 568 ml greater. Treatment consisted of manual lymphatic drainage and intermittent sessions of pneumatic compression with the LymphaPress device. This led to an average decrease in arm volume of 170 ml, with improvement of arm mobility and a drastic reduction in shoulder pain. In conclusion, lymphedema of the arm can cause severe shoulder trauma, pain and disability. Proper physiotherapy can reduce these effects. Patients should be referred for early treatment and follow-up to avoid permanent damage to the shoulder muscles.