Microcirculation is a rather new field which has been of predominant interest to basic scientists, linking togeth~r technical, hemodynamic, and biochemical aspects. The fmdings elaborated, however, are not only of theoretical interest, but bear in addition great clinical implications. In clinical cardiology this became quite evident by the use of tracers in order to study myocardial perfuSion and by the deSCription of certain clinical entities - such as angina with normal coro nary arteries - which are best explained by "disturbed microcirculation". With respect to this new developing theoretical and clinical field of cardiac microcirculation it was the aim of the Microcirculation Working Group of the European Society of Cardiology to have a symposium on which all different but clinically relevant aspects of cardiac microcirculation will be covered. This symposium, held in Heidelberg in January 1980, was planned not only for the exchange of concepts and ideas, but was expected to be in addition partially a teaching session; the basic scientists should be directed toward a better under standing of the clinical problems, and the clinicians should learn more about the basic mechanisms regulating substrate and ion exchange in such an impor tant organ as the heart, and furthermore the theoretical limitations of some of the diagnostic and therapeutical procedures should be taught. Without a lot of help we would never have succeeded in organizing the sym posium and editing its results.