The activities of the International Union Against Cancer (UJ.c.c.) are carried out by the Commission on Cancer Research and the Commission on Cancer Control. The Commission on Cancer Control is concerned with the detection, treatment and social campaign against cancer and, to facilitate its work, has committees on cancer detection, cancer prevention, patient care, professional education, public education and voluntary organizations. The Committee on Cancer Detection is concerned with programmes for the early diagnosis and registration of cancer and of pre-cancerous conditions with the object of achieving a reduction in cancer morbidity and mortality. The Committee is expected to study such programmes in the various countries and collect and evaluate the data and experience available. To this end meetings of the Committee were held in New York (1963), Oslo (1964) and Toronto (1965). This report is the result of these meetings and represents a considerable effort on the part of the Committee members. Dr. E. PEDERSEN (Chairman) - Oslo, Norway Dr. A. PHILLIPS (Secretary) - Toronto, Canada Dr. E. DAY - New York, U.S.A. Dr. M. GAITAN-YANGUAS - Bogota, Colombia Dr. R. GERARD-MARCHANT - Villejuif, France Dr. K. GROSS - Prague, Czechoslovakia Dr. T. KUROKAWA - Tokyo, Japan Dr. A. NOVICKOW - Moscow, U.S.S.R. Dr. L. ROBBINS - Washington, U.S.A. Dr. G. TERZANO - Buenos Aires, Argentina.