The World Health Organization (WHO) is the agency of the United Nations with primary responsibility for international health matters and public health. Through the exchange of the knowledge and experience of health professionals from 165 nations WHO promotes comprehensive health services worldwide. As a part of this effort WHO has in recent years been concerned with improving the availability and utilization of diagnostic imaging, especially as it relates to health services in developing countries. Having devised and specified suitable basic radiographic equipment (the WHO BRS) a WHO Scientific Group was convened in 1982 to study the utilization of radiographic procedures and to to recommend their more efficacious and rational use. Then in 1984, recognizing the implications of newer imaging technology on world health, a second WHO Scientific Group considered the design, impact and future use of ultrasonography and computed tomography in developing countries. The findings of these scientific groups were published as part of the WHO Technical Report Series which makes available the recommendations of such international groups of experts. Although some of the needs of children were considered in these previous Technical Reports, WHO felt that the size and socioeconomic importance of the paediatric population worldwide warranted a further study and report to address the particular technical and clinical problems of diagnostic imaging in the paediatric age group. Thus a third WHO Scientific Group met in Geneva from 18 to 24 November 1985 to review established practices and experience in paediatric imaging throughout the world; and to recommend rational guidelines for diagnostic imaging for children to age 14 years.(ABSTRACT TRUNCATED AT 250 WORDS)