Evaluation of a new fiberoptic pressure recording system for cardiovascular measurements in mice. We have tested a new fiberoptic pressure recording system, SAMBA®, with a thin fiber (outer diameter; OD=0.25 mm) and a pressure sensor (length and OD=0.42 mm) attached to the end. The accuracy of the pressure system tested in vitro was good, with a coefficient of variation of 2.54 % at 100 mmHg. The drift was less than 0.45 mmHg per hour, and the temperature sensitivity was about 0.07 mmHg per 1°C between 22 and 37°C. The frequency response characteristics were similar to a 1.4 F Millar catheter (0-200 Hz). Introduction of the Samba-sensor from the right carotid artery into the left ventricle in six mice caused no drop in mean aortic pressure, whereas introduction of a 1.4 F Millar catheter (OD=0.47 mm; n=6) caused a drop in pressure from 91.6 ± 9.2 to 65.1 ± 6.2 mmHg; p < 0.05. Thus, the Samba-sensor system may represent a new alternative to assess hemodynamic variables in the murine cardiovascular system.