In a retrospective study of 1 094 patients treated for Hodgkin's disease between 1963 and 1976, we have observed 65 malignant complications including 28 granulosis acute leukemias and 37 solid tumors. The actuarial 10 year risk of developing acute leukemia is 4.7 per cent; and 5.4 per cent for solid tumors. These figures vary according to the medications received. They are more important in the case of polychemotherapy, particularly for acute leukemia, thus confirming the specific role of alkyl agents. While the course of solid tumors does not seem to differ from that of identical primitive tumors; on the other hand, induced leukemia seems to have a more perjorative prognosis than spontaneous leukemia and they are often announced by cytopenia. The overall risk of developing secondary cancer is multiplied by 2.4 compared to the normal population; that of developing acute leukemia is multiplied by 9.3. In order to reduce this risk, active non alkyl agents of limited duration must be advocated. Irradiation fields must also be reduced.