Secondary lymphoedema (SL) is one of the most common and, at the same time, most significant consequences and complications of modern oncological therapy. Although a thorough patient history and physical examination are sufficient to substantiate a suspicion, it is essential to perform functional imaging of the lymphatic system for a targeted diagnosis and determination of severity. For this purpose, techniques such as MR and ICG lymphography as well as ultra-high-frequency ultrasound examinations have been developed and validated in recent years. The selective use of these techniques has allowed for individualized indications and successful stage-dependent treatment using (super)microsurgical techniques to restore regional lymphatic drainage in the context of intensified conservative therapy.