Breast cancer is the most common cancer in women. Lymphoedema in the arm is a well-known side effect of breast cancer treatment and ranks high among the serious concerns of survivors. Thus, it is important to diagnose arm lymphoedema at an early stage and start conservative treatment when lymphoedema is still minimal or mild, thereby preventing development or deterioration of arm lymphoedema. Screening of high-risk patients is useful for early diagnosis, including both objective measurement and the patients experience. Compression garment is the most important component in treatment. If arm lymphoedema is early diagnosed and treated with compression garment with regular follow-up and garment renewal it cam be kept on a very low level, for a long time.