Cardiomyopathies are certain heart diseases of unknown etiology and pathogenesis, occurring mostly in tropical and subtropical areas, where they constitute a major clinical problem and sometimes a public health problem. The need for international co-operation in the study of such forms of heart disease has long been recognized and WHO convened informal meetings of investigators on various aspects of the subject in 1964, 1965 and 1966. Out of these have arisen co-operative studies co-ordinated by WHO. In November 1967 a fourth informal meeting was held in Kingston, Jamaica, to review the following topics: the progress reports from all co-operating laboratories; the different types of cardiomyopathies; past experience with cardiac registries, and the diagnostic importance of coronary angiography. Steps were taken towards the formulation of a standard terminology, since too many confusing names are currently employed to mean "cardiomegaly of unknown origin". A common name, "idiopathic cardiomegaly", was therefore suggested for future use.The account presented here was prepared by Dr Z. Fejfar, Chief Medical Officer, Cardiovascular Diseases, World Health Organization, Geneva, on behalf of the other participants and is a précis of some of the information that was exchanged, some of the views that were expressed and of the suggestions that were made.