A computer-assisted learning program to demonstrate the pharmacological actions of drugs on the isolated, perfused mammalian heart is described. The program is based on a series of experiments (the action of a range of drugs/drug combinations; the action of ions; the effects of increasing preload) which may be performed on the Langendorff heart preparation. Simulated responses (contractile force, heart rate and coronary blood flow) are presented, in high-resolution graphics, for each experiment in a form comparable to a chart recorder display. The program is driven from an easy-to-use menu and contains textual information describing the preparation, the apparatus and the method. A HELP option, in the form of an editable text window, is also available. The potential for using this program in undergraduate teaching and its ability to meet the teaching objectives of laboratory-based practical sessions are discussed.