In Denmark, 6.6% of all malignant neoplasms among men and 5.5% among women occur in the lymphatic and haematopoietic tissues. Most are generalized when diagnosed, although lymphomas are sometimes confirmed to one region. Treatment has been predominantly by chemotherapy since the 1960s, and is often combined with radiation for lymphomas and myeloma. The five-year survival rates for non-Hodgkin's lymphoma improved by 20% between 1970 and 1987. An improvement in survival from Hodgkin's disease began earlier, with a relative five-year survival rate of about 30% in 1960 and of 72% in 1983-87. Survival was better for younger patients (< 50 years) with stage I-II disease, the relative five-year survival rates being 83-93% in 1983-87. For cases of leukaemia much of the improvement in survival rates was founded in 1960s on success in the treatment of childhood leukaemia (acute lymphatic leukaemia); the relative five-year survival rates for children under 10 years of age increased from 12% to 75-80%. Smaller improvements were seen in survival from other types of leukaemia, including the chronic forms. Thus, even for chronic lymphocytic leukaemia, which has a favourable prognosis but is regarded as incurable, improvements in survival rates were seen, which may be attributed to chemotherapeutic treatment or earlier diagnosis. It was not surprising that the dramatic improvement in survival rates coincided with the introduction of chemotherapeutic treatment regimes, as reported previously in clinical series. Acute and chronic cytotoxic side-effects are of concern, and, since both cytotoxic drugs and radiation are potent carcinogens, second primary cancers have been reported to be induced by treatment of cancers (Storm & Prener, 1985). The improvements in the survival rates for the haematopoietic malignancies, however, outweigh the de novo cancer risk related to therapy.