Manual lymphatic drainage is used in physiotherapy of limb lymphedema in combination with other physical techniques. In order to assess the effectiveness of the method, 47 patients with upper limb lymphedema after radiosurgical therapy for breast cancer underwent lymphoscintigraphy. The examination was performed after subcutaneous injection of technetium-labeled colloid via the fourth and first interdigital space on the hand of the limb with lymphedema. The level of the technetium label was compared on scintigraphies performed before and after manual lymph drainage. Results were analyzed as a function of the clinical characteristics of the edema. Manual lymphatic drainage produced an effective progression of the label in 25 cases (53.2%), independent of radiotherapy. Contralateral lymph nodes were reached in 5 cases and the homolateral internal mammary nodes in 2. These nodes were visualized only after manual lymphatic drainage. The visualization of the drainage routes in unexpected areas demonstrated the effectiveness of the technique in stimulating accessory routes useful for resorption of lymphedema. The use of two injection sites on the hand is also discussed. This study demonstrated the effect on a single session of manual lymphatic drainage and should be completed with an assessment of a complete series of manual lymphatic drainages.