The isolated heart is deservedly one of the most popular experimental models in cardiovascular research, both in terms of cost and the quality and quantity of data it provides. However, it is a deceptively simple model, capable of throwing many problems in the path of the inexperienced or unwary perfuser. The following article discusses the advantages and disadvantages of the various types of isolated heart perfusion (Langendorff and working; blood and buffer perfused). We attempt to give an insight into the many factors which must be taken into consideration when first establishing these preparations, we identify the range of indices that can be measured and the potential pitfalls which, with a little care, can be readily avoided.