Therapeutic fibrinolysis represents the only logical means of curing thromboses, by assuring the destruction of the thrombus. This kind of therapy, which was introduced clincally over 10 years ago, has been used on only a limited scale because of the high risk of haemorrhage and the need for highly specialized laboratory control tests. Different methods of administration, overcoming one or other of these disadvantages, have resulted recently in its wider use but this has been accompanied by a reduction in efficacity. The very satisfactory clinical results obtained in some cases remain limited and thus in this context the indications should not be restricted.