A randomised, double-blind, cross-over trial was performed on 26 patients with post-mastectomy lymphoedema of the arm, and 14 with lymphoedema of the leg. For 6 months, patients took O-(β-hydroxyethyl)-rutosides (oxerutin; "Paroven®", "Venoruton®", Zyma) in doses of 3 g/day, or the placebos; then they took the reverse. Measurements (volume, circumferences, tonometry and skin temperature) were made monthly. The active drug reduced the volumes of the limbs (p<0.05 to 0.01) and their circumferences (p<0.05 to 0.001). It increased the softness of the limbs, as shown by the increases in the tonometry values (p<0.01 to 0.001). There was a lowering of the elevated skin temperatures (p<0.05 to 0.001). Patients reported increased comfort and freedom of movement, a lessening of their bursting pains, heaviness and tension (p<0.05 to 0.01), and an increased mobility of their limbs (p<0.0001). Most patients (70%) preferred the active drug (p<0.0001). An increase in general well-being was reported by 97% of patients when taking the active drug compared with 4% for the placebo (p<0.0001).