We compared the intracardiac and intravascular pressures obtained by a conventional strain gauge transducer (CT) with a recently developed disposable high-fidelity transducer catheter (DT) during cardiac catheterization. CT was positioned at the patient's midchest level. The pressure measurements obtained by DT compared favorably with those of CT. Femoral arterial pressures by the two methods showed no statistical difference. Right heart pressures were similar using both transducers. However, right ventricular pressures by DT in five of eight patients were lower than that from CT. Higher pulmonary arterial pressures were noted in two of seven patients and higher pulmonary capillary wedge pressures were seen in four patients using DT compared to CT. None of these differences were of statistical significance. These pressure differences may be due to transducer position. Because the midchest position of CT does not precisely define the anatomic location of the cardiac chamber being studied, pressure measurements can be overestimated or underestimated. DT eliminates this problem, as well as overshooting and concern with air bubbles in the catheter system commonly associated with CT. Therefore DT may provide accurate hemodynamic measurements. It would appear to be useful regardless of patient position and may be useful in ambulatory hemodynamic determinations.