Scoparone (6,7-dimethoxycoumarin 1.25, 2.5, 5 mg.kg-1) influenced the cardiohemodynamic functions in anesthetized cats. After i.v. injection the LVP-dP/dt loops and blood pressure were decreased. Both the contractile and relaxant functions of the left ventricle were inhibited. These were demonstrated by the reduction of dP/dtmax, Vmax, Vce-dp40, LVSP, prolongation of LVET, diminution of -dP/dtmax, and extension of the constant time of isometric diastolic pressure decay (T value). The preload of the left ventricle, LVEDF, was raised and the afterload (MAP, TPB) was decreased: The systolic volume, systolic index, cardiac output, and cardiac index were decreased slightly. The parameters TTI and TTI x HR, which reflect the myocardial oxygen consumption, were reduced. Furthermore, the heart rate was decreased at 5 mg.kg-1. The results indicate that scoparone could suppress the myocardial activity.