Forty-eight patients less than 65 years old, suffering non-Hodgkin's malignant lymphomas with one or more criteria of poor prognosis, were priorly placed in complete remission by an association of chemo + radio + chemotherapy. They were then randomized to receive either BCG in weekly scarifications for 3 years or no further treatment. Five patients were excluded (four after pathological reassessment); 43 are thus evaluable. There were 13 relapses out of 23 control patients and three relapses out of 20 treated patients (0.01 less than P less than 0.025). This difference is more distinct for clinical stages I and II (0.01 less than P less than 0.025) than for stages III and IV (not significant). Eight patients died in the control group whereas there was only one death in the treated group (0.025 less than P less than 0.05). These results indicate than BCG is useful in maintaining remission in about 40% of the cases and also in increasing their survival, especially in patients with clinical stages I or II.