In our experience the prognosis of hematological relapse in patients with acute lymphatic leukemia treated according to the Pinkel programme is very bad. It may be a little better for patients in whom relapse occurred after the end of therapy and who were submitted to intensified cytostatic treatment. The chances for achieving a second long-term remission, if the relapse is confined to the CNS, are also better. This is true particularly for those patients who in addition were given radiotherapy. In recurrence in the testes radiotherapy alone will not suffice and additional intensified cytosatic treatment should be considered.