The lymphatic origin of chronic edema of the lower limbs was identified by lymphoscintigraphic exploration. Patients underwent therapy involving 8 days of manual lymph drainage combined with elevation of the limbs during rest periods and double compression bandaging. Manual drainage increased lymph flow in 16 limbs, implying that the edema resulted from a functional lymphatic anomaly. In contrast, manual drainage did not increase lymph flow in 9 limbs, suggesting a structural anomaly of the lymphatics. Hence, the same clinical picture corresponded to two different lymphatic anomalies, distinguished by lymphoscintigraphy. However, the therapeutic results were independent of the lymphoscintigraphic results. Increased lymph flow is therefore not the only explanation for the decrease in edema during therapy.