7 children suffering from acute lymphatic leukemia (ALL) and non-Hodgkin's lymphoma, resp., were injected intrathecally with /sup 198/Au colloid for metaphylaxis. The children had been cured of 8 relapses of miningosis and received irregularly intrathecal injections of methotrexate for cerebral maintenance therapy. The median cerebral period of remission was 52 weeks. 1 child suffering from ALL had been free from meningosis relapses for 128 weeks. Continuous cytostatic therapy is necessary for methaphylaxis. However, despite of the good results presented, /sup 198/Au colloid can not be recommended for long-term therapy because radiation injuries are to be expected.