A fully implantable telemetric system for the measurement of cardiac left ventricular pressure and derived parameters in conscious dogs is presented. It provides the following advantages: ethical acceptability, scientific relevance, economical experimentation, avoidance of stress-induced situations for the animal and experiments without anesthesia or sedation. The system has an operation time which allows the sequential pharmacological evalution of many drugs in individual dogs, shown by testing the effect of the positive inotropic agent, dobutamine, and the Ca antagonists, verapamil and nifedipine.