The principal purpose of a NATO (North Atlantic Treaty Organization) Advanced Research Workshop, a part of the NATO Advanced Study Institutes Programme, is to: (a) exchange thoughts at the frontiers of knowledge or at the frontiers of two (or more) fields or sectors; (b) review and assess the state of the art; (c) formulate recommendations for future research directions; (d) formulate plans for large international scientific experiments. The aim of the ARW on "Microvascular, rheological, metabolic and heat-transfer aspects of the heart: relation to ischaemia and thrombosis", convened in Chateau de Bonas, July 4-11, 1982, was to describe functions and performance of the heart in an interdisciplin ary effort, involving cardiologists, pathologists, biochemists, haemorheologists, physiologists, pharmacologists and bioengineers; to explore interactions between such subfields as blood rheology, micro circulation and ischaemia of the myocardium, heat transfer, heat work and performance as a pump, effect of -metabolites and ion transfer, mechanism of sudden death, protein synthesis and protein molecular transformations. One of the purposes of the Convenor was to relate clinical haemorheology to the heart energetics and heart metabolism. This was only partly established, as difficulties of communications between different fields, difficulties of semantics and of specialized out looks could not be overcome within a -few days. Nevertheless, a gate was opened for communications interchange in the future. There was even a problem within each specialty, and as is rather common, quite diverse views have been expressed. This, of course, is quite normal in the progress of science.