The contractile function of the non-infarcted myocardium was examined in adult cats following myocardial infarction produced by ligation of several branches of the LAD and circumflex coronary artery. Two and seven days following infarction, after determination of intracardiac pressures, papillary muscles were excised from the non-infarcted portion of the right ventricle and transferred into a myograph for analysis of contractile function. One week following infarction, force-velocity relations of the surviving myocardium showed a shift downward and to the left in comparison to sham-operated controls. At the same time, there was a decline in actively developed force at Lmax to be deserved, which appeared to be caused by a decrease in the rate of force development. Two days following infarction, similar changes were to be observed, although to a lesser extent. There appears to be a distinct loss of contractility in the remaining viable myocardium following experimental infarction.