This World Health Organization (WHO) report on the proceedings of a Working Group on Child Cancer Control was prepared by the WHO Regional Office for Europe. The working group met in Prague in April 1977 and was comprised of representatives from 14 European countries. Its task was to review existing methods of child cancer control, the efficacy of treatment and management methods, and the possible role of environmental factors. The report presents numerous tables of child cancer morbidity and mortality figures in the European region, and evaluates the positive and negative consequences of treatment of different kinds of malignant diseases and after effects of treatment. Prevention is considered from different points of view: genetic, physical, chemical, and biological. Identification of high-risk groups, effects of environmental factors, and early screening and diagnosis are briefly discussed. Special child-oriented organization of cancer control, including registraction, nomenclature classification and relationship of child cancer control to other health services, is discussed at length. Recommendations are made pertaining to future directions for research in cancer treatment, registration, nomenclature and classification, location of paediatric cancer units, evaluation of delayed side effects of treatment, rehabilitation measures and prevention and early diagnosis. (CM)