The authors discuss 90 cases of iatrogenic incidence following either sclerotherapy (46 cases), or surgery (44 cases) performed on varices of the lower members. Some such incidence may be extremely serious (5 deaths, 15 amputations), or much less so. They may be due to the general risk of therapy, or to imperfect technique or professional error. The authors analyse the various aspects of these causes. Everything possible must be done to prevent incidence or, if they occur, to treat them effectively. The authors will have reached their goal if they manage to provide more complete information on the very real risks incurred sometimes by treatment; these are undoubtedly rare, but are occasionally mortal or of major functional importance, whereas the illness itself is common, disabling, but almost always without serious consequences.