The aim of this work is to explore the patients operated on for a femoro popliteal bypass (FPB) with lymphoscintigraphy (LS) of the lower limbs. Data concerning 35 limbs from 33 patients operated on for a FPB have been included in a prospective study. Superficial and deep LS have been performed by injecting 74 MBq 99mTc-Rhenium Sulphide Colloid into the subcutaneous tissue of the first interdigital space and of the lateral malleolus region respectively. Both superficial and deep LS have been performed before and after surgery. A postoperative oedema was found in 17 of the 35 limbs. The value of the lymphatic flow indices and their variation after surgery do not significantly differ between the oedematous and non oedematous groups. Thirteen of the 17 limbs with oedema have presented an interruption of the lymphatic circulation or a diffuse activity outside the lymphatic vessels on the postoperative superficial and/or deep LS. This proportion is only 1/18 in the non oedematous group. The difference between the two groups is highly significant (P less than 0.001). By contrast, the proportion of lymph cyst does not differ significantly between the two groups. In conclusion, this study confirms the close relationship between the oedema following FPB and surgical damage to the lymphatics.