Neoplasm therapy is restricted by the haematological side effects of tumour-destructive therapy, requiring expensive supportive care to some extent to overcome and treat leucopenia and its consequences. An effective and very cost-effective alternative for treating neutropenia is to administer lithium carbonate. Lithium leads to a release of hematopoietic growth factors (CSF) and therefore to proliferation of neutrophil granulocytes. Normally, recombinant CSF is only administered when there are indications of severe neutropenia because of the high costs involved, all the more evident in the long-term treatment of persistent leucocytopenia. On the other hand, CSF and leucocytes play an essential role in tumour immunology and with regard to response rates to cytostatic drugs. Lithium salts have shown that they can increase the number of neutrophil granulocytes quite significantly and, to a lesser extent, the number of eosinophil granulocytes and lymphocytes as well. The average number of erythrocytes does not change significantly. Patient tolerability to lithium carbonate therapy is very good. It can be used to treat patients with chronic leucopenia following chemotherapy or radiotherapy extremely cost-effectively. Unfortunately this treatment has not won acceptance in clinical oncology in the face of highly cost-intensive treatment with recombinant CSF.