The 11 th meeting in "Modern Trends in Human Leukemia" took place from June 19 to 21, 1994 in Wilsede in the middle of the Liineburger Heide, South of Hamburg. Interwoven with the Leukemia program was the Nato-sponsored Symposium of the ASI-Series "Gene Technology in Analysis of Malignant and Inherited Human Diseases Related to Development" . The Wilsede meeting was continued on a ship of the Neva leading through lake Ladoga and lake Onega. The topics of both meetings included discussion on recent progress isolation and development of hematopoietic stem cells, genes crucial for development and diseases, methods of gene transfer, application of gene transfer; oncogenes and anti-oncogenes as targets for gene therapy; receptors and their ligands in normal development and diseases, immunology and immunotherapy, radiation biology, clinical leukemias and bone marrow transplantation. The Nato workshop concentrated not only on analysis of cell systems useful for somatic gene therapy, but also on actual themes directly related to correction of human diseases. The latter aspects emphasized themes related to biotechnology, the first part was by nature more general. We also included a few contributions that discussed perspectives for the future of gene therapy and possible relationships to evolution.